251y0631s1 12/12/06 Individual Solutions to Take-home Warning – This document has the worksheets for every version of the Take-home Problems. At last count it was about 70 pages long. Please only print the solution for your version of the problem. Most versions are headed with problem and version number. Individual solutions to Take-home Problem 1 for Versions 0 through 9 begin on page 5 and go to page 24. Individual solutions to Take-home Problem 2 for Versions 0 through 9 begin on page 28 and go to page 57. Individual solutions to Take-home Problem 3 for Versions 0 through 9 were not computed correctly, and only the solution to Version 0 begins on page 64. 1 251y0631s1 12/12/06 1) Bassett et al. give the following numbers for the year and the number of pensioners in the United Kingdom. Pensioners are in millions. The 2000 number is a bit shaky, so subtract the last digit of your student number divided by 10 from the 12.00 that you see there. Label your answer to this problem with a version number. (Example: Good ol’ Seymour’s student number is 123456, so the 12.000 becomes 12.000 0.6 = 11.400 and he labels it Version 6.) 'Pensioners' is the dependent variable and 'Year' is the independent variable, so what you are going to get is a trend line. If you don’t know what dependent and independent variables are, stop work until you find out. 1 2 3 4 5 6 7 8 Year Pensioners 1966 1971 1975 1976 1977 1978 1979 2000 6.679 7.677 8.321 8.510 8.637 8.785 8.937 12.000 Bassett et. al. strongly suggest that you change the base year to something other than the year zero. They recommend that you subtract 1970 from every number in the ‘Year’ column, so that 1966 becomes -4 and 2000 becomes 30. This will make your computations easier. a. Compute the regression equation Y b0 b1 x to predict the number of pensioners in each year. (3).You may check your results on the computer, but let me see real or simulated hand calculations. Solution: Version 0 i XY X Y X2 Y2 1 2 3 4 5 6 7 8 -4 1 5 6 7 8 9 30 62 6.679 7.677 8.321 8.510 8.637 8.785 8.937 12.000 69.546 To summarize n 8, Y 2 -26.716 7.677 41.605 51.060 60.459 70.280 80.433 360.000 644.798 44.609 58.936 69.239 72.420 74.598 77.176 79.870 144.000 620.848 X 62, Y 69 .546 , XY 644 .798 , X 2 1172 and 620 .848 . df n 2 8 2 6. X 62 7.75 Means: X n 8 X Spare Parts: SS x 2 Y Y 69.546 8.69325 n 8 nX 1172 87.752 691.50 2 Y nY 620.848 88.69325 16.2673 SST XY nXY 644 .798 87.75 8.69325 105 .8165 SS y S xy 16 1 25 36 49 64 81 900 1172 2 2 2 (Total Sum of Squares) Coefficients: b1 S xy SS x XY nXY X nX 2 2 105 .8165 0.1530 691 .500 b0 Y b1 X 8.69325 0.1530 7.75 7.5075 So our equation is Yˆ 7.5075 0.1539 X b. Compute R 2 . (2) Solution: SSR b1 Sxy 0.1530 105 .8165 16.1899 R2 S xy 2 105 .8165 2 .9954 SSR b1 S xy 16 .1899 .9952 or R 2 SST SSy 16 .2673 SS x SS y 691 .516 .2673 2 251y0631s1 12/12/06 c. Compute s e . (2) Solution: SSE SST SSR 16.2673 16.1899 .07740 s e2 SSE .07740 .01290 s e .01290 0.11358 n2 6 Note also that if R 2 is available s e2 SS y 1 R 2 n2 16.2673 1 .9954 .01247 6 and s e .01247 0.11168 . I will compromise and use s e2 .0127 1 0.0127 d. Compute s b1 and do a significance test on b1 . (2) Solution: s b21 s e2 0.00001837 SS x 691 .5 b 0 0.1539 s b 0.00001837 0.004286 . t 1 35 .908 . If we assume that .05 , compare this 1 s b1 0.004286 6 with t .025 2.447. Since the computed t is larger than the table t in absolute value, we reject the null hypothesis of no significance and say that the slope is significant. e. Use your equation to predict the number of pensioners in 2005 and 2006. Using the 2006 number, create a prediction interval for the number of pensioners for that year. Explain why a confidence interval for the number of pensioners is inappropriate. (3). Solution: Our base year was 1970 so the value of X for 2005 is 2005 – 1970 = 35. Our equation is Yˆ 7.5075 0.1539 X and for 2005 it gives Ŷ 7.5075 0.153935 12.894. Since the slope is 0.1539, add this to the 2005 value to get 13.048 for 2006. The formula for the 1 X X 2 Prediction Interval is Y0 Yˆ0 t sY , where sY2 s e2 0 1 . For 2006, X 0 36 . It’s time to n SS x remember that s e .01247 0.11168 , n 8, X 7.75 and SS x X 2 nX 2 691 .50 . 1 36 7.75 2 So sY2 .1247 1 .1247 0.1250 1.1541 1 .1247 2.2791 0.2842 8 691 .5 s 0.2842 0.5331 . We already know that t 6 2.447 and that for 2006 Yˆ 13 .048 . So that our Y .025 prediction interval is Y0 Yˆ0 t sY 13.048 2.4470.5331 13.048 1.304 , or between 11.7 and 14.3 million people. The confidence interval is inappropriate for this type of problem. To use the problem demonstrated in class, a confidence interval done when X 0 5 gives us a likely range in which the average number of children will fall for the average couple that wants 5 children. The prediction interval gives us a likely range in which the number of children will fall for one couple that wants 5 children. There is no average year 2006, since it will be 2006 only once, so an interval for an average makes no sense. f. Make a graph of the data. Show the trend line clearly. If you are not willing to do this neatly and accurately, don’t bother. (2) Suggestions: I don’t have the graphical power to do this but here’s what I would do. Since our years vary from 1966 to 2006 and the number of pensioners varies from 6.68 to a projected 13.0 million, your x axis should be marked from 1966 to 2006, but I would probably only mark the years 1970 to 2010 by 5-year intervals. I might consider stretching the whole thing out to 2050 because of the next question. The y-axis might go from 6 to 14 million with marks for every two million. I can plot the regression line Yˆ 7.5075 0.1539 X by noting that for 1970 it gives us 7.5 million which grows to 13 million in 2006. these two points can be connected to give us the regression line and the 8 points that we used to get the regression equation can be plotted around it. g. What percent rise in pensioners did the equation predict for 2006? What percent rise does it predict for 2050? The population of the United Kingdom grew at roughly 0.31% a year over the last quarter of the 20 th century. Can you intelligently guess what is wrong? (1) Solution: Our base year was 1970 so the value of 3 251y0631s1 12/12/06 X for 2049 is 2049 – 1970 = 79. Our equation is Yˆ 7.5075 0.1539 X and for 2049 it gives Yˆ 7.5075 0.153979 19.666 . Since the slope is 0.1539, add this to the 2049 value to get 19.819 for 2050. We thus have the following. Year Number Per cent growth. 2005 12.894 2006 13.048 1.19 2049 19.666 2050 19.819 0. 78 It is reasonable to expect the growth rate to fall as the absolute number of additional pensioners stays constant but the number of pensioners grows. However, we are predicting that for an 80 year period the number of pensioners will grow faster than population. Aside from the fact that this results in a substantial rise in the number of pensioners per worker that may be politically impossible, it’s hard to believe that the country will produce old people at a rate substantially higher than population grows for over 80 years. This is a basic problem with using a trend line to make predictions. A given slope may be appropriate for a long while, but it is no more appropriate to say it will last forever, than it is to say that Wal-Mart’s sales will continue to grow at a rate way above total retail sales for decades. Sooner or later Wal-Mart’s sales will be such a large part of retail sales that the only way to grow Wal-Mart’s sales at such a high rate is to grow all retail sales at a higher rate, which just won’t happen if we are all drawing our wages from Wal-Mart. ————— 11/30/2006 10:41:39 PM ———————————————————— Welcome to Minitab, press F1 for help. 4 251y0631s1 12/12/06 Take-Home Problem 1, Version 0 MTB > WOpen "C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06031000.MTW". Retrieving worksheet from file: 'C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06031-000.MTW' Worksheet was saved on Wed Nov 29 2006 Results for: 252x06031-000.MTW MTB > Execute "C:\Documents and Settings\RBOVE\My Documents\Minitab\252sols06031.mtb" 1. Executing from file: C:\Documents and Settings\RBOVE\My Documents\Minitab\252sols06031.mtb Data Display K11 K12 K13 K14 K15 3.00000 4.00000 5.00000 6.00000 7.00000 Regression Analysis: pensioners versus year The regression equation is pensioners = 7.51 + 0.153 year Predictor Constant year Coef 7.50731 0.153025 S = 0.111940 SE Coef 0.05152 0.004257 R-Sq = 99.5% Analysis of Variance Source DF SS Regression 1 16.193 Residual Error 6 0.075 Total 7 16.268 Obs 1 2 3 4 5 6 7 8 year -4.0 1.0 5.0 6.0 7.0 8.0 9.0 30.0 pensioners 6.6790 7.6770 8.3210 8.5100 8.6370 8.7850 8.9370 12.0000 T 145.71 35.95 P 0.000 0.000 R-Sq(adj) = 99.5% MS 16.193 0.013 Fit 6.8952 7.6603 8.2724 8.4255 8.5785 8.7315 8.8845 12.0980 F 1292.24 SE Fit 0.0638 0.0489 0.0413 0.0403 0.0397 0.0396 0.0399 0.1027 P 0.000 Residual -0.2162 0.0167 0.0486 0.0845 0.0585 0.0535 0.0525 -0.0980 St Resid -2.35R 0.17 0.47 0.81 0.56 0.51 0.50 -2.20RX R denotes an observation with a large standardized residual. X denotes an observation whose X value gives it large influence. Predicted Values for New Observations New Obs Fit SE Fit 95% CI 1 12.0980 0.1027 (11.8469, 12.3492) 2 12.8632 0.1226 (12.5633, 13.1631) 3 13.0162 0.1266 (12.7064, 13.3260) 4 19.5963 0.3059 (18.8478, 20.3447) 5 19.7493 0.3101 (18.9905, 20.5080) 95% (11.7264, (12.4570, (12.6027, (18.7993, (18.9426, PI 12.4697)X 13.2693)X 13.4297)XX 20.3932)XX 20.5560)XX X denotes a point that is an outlier in the predictors. XX denotes a point that is an extreme outlier in the predictors. 5 251y0631s1 12/12/06 Values of Predictors for New Observations New Obs year 1 30.0 2 35.0 3 36.0 4 79.0 5 80.0 Data Display Row 1 2 3 4 5 6 7 8 year -4 1 5 6 7 8 9 30 pensioners 6.679 7.677 8.321 8.510 8.637 8.785 8.937 12.000 _xsq 16 1 25 36 49 64 81 900 _xy -26.716 7.677 41.605 51.060 60.459 70.280 80.433 360.000 _ysq 44.609 58.936 69.239 72.420 74.598 77.176 79.870 144.000 Data Display sum_y sum_x sum_xsq sum_xy sum_ysq 69.5460 62.0000 1172.00 644.798 620.848 Data Display _n _SSX _SSY _SSxy _xbar _ybar 8.00000 691.500 16.2677 105.817 7.75000 8.69325 6 251y0631s1 12/12/06 Take-Home Problem 1, Version 1 MTB > WOpen "C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06031001.MTW". Retrieving worksheet from file: 'C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06031-001.MTW' Worksheet was saved on Wed Nov 29 2006 Results for: 252x06031-001.MTW MTB > exec '252sols06031' Executing from file: 252sols06031.MTB Data Display K11 K12 K13 K14 K15 3.00000 4.00000 5.00000 6.00000 7.00000 Regression Analysis: pensioners versus year The regression equation is pensioners = 7.52 + 0.150 year Predictor Constant year Coef 7.51975 0.149807 S = 0.126744 SE Coef 0.05834 0.004820 R-Sq = 99.4% Analysis of Variance Source DF SS Regression 1 15.519 Residual Error 6 0.096 Total 7 15.615 T 128.90 31.08 P 0.000 0.000 R-Sq(adj) = 99.3% MS 15.519 0.016 F 966.06 P 0.000 Obs year pensioners Fit SE Fit Residual St Resid 1 -4.0 6.6790 6.9205 0.0722 -0.2415 -2.32R 2 1.0 7.6770 7.6696 0.0554 0.0074 0.07 3 5.0 8.3210 8.2688 0.0467 0.0522 0.44 4 6.0 8.5100 8.4186 0.0456 0.0914 0.77 5 7.0 8.6370 8.5684 0.0450 0.0686 0.58 6 8.0 8.7850 8.7182 0.0448 0.0668 0.56 7 9.0 8.9370 8.8680 0.0452 0.0690 0.58 8 30.0 11.9000 12.0140 0.1162 -0.1140 -2.25RX R denotes an observation with a large standardized residual. X denotes an observation whose X value gives it large influence. Predicted Values for New Observations New Obs Fit SE Fit 95% CI 95% PI 1 12.0140 0.1162 (11.7296, 12.2984) (11.5932, 12.4347)X 2 12.7630 0.1388 (12.4234, 13.1026) (12.3031, 13.2229)X 3 12.9128 0.1433 (12.5620, 13.2635) (12.4446, 13.3810)XX 4 19.3545 0.3463 (18.5071, 20.2019) (18.4521, 20.2569)XX 5 19.5043 0.3511 (18.6452, 20.3634) (18.5909, 20.4177)XX X denotes a point that is an outlier in the predictors. XX denotes a point that is an extreme outlier in the predictors. 7 251y0631s1 12/12/06 Values of Predictors for New Observations New Obs year 1 30.0 2 35.0 3 36.0 4 79.0 5 80.0 Data Display Row 1 2 3 4 5 6 7 8 year -4 1 5 6 7 8 9 30 pensioners 6.679 7.677 8.321 8.510 8.637 8.785 8.937 11.900 _xsq 16 1 25 36 49 64 81 900 _xy -26.716 7.677 41.605 51.060 60.459 70.280 80.433 357.000 _ysq 44.609 58.936 69.239 72.420 74.598 77.176 79.870 141.610 Data Display sum_y sum_x sum_xsq sum_xy sum_ysq 69.4460 62.0000 1172.00 641.798 618.458 Data Display _n _SSX _SSY _SSxy _xbar _ybar 8.00000 691.500 15.6151 103.592 7.75000 8.68075 8 251y0631s1 12/12/06 Take-Home Problem 1, Version 2 MTB > WOpen "C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06031002.MTW". Retrieving worksheet from file: 'C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06031-002.MTW' Worksheet was saved on Wed Nov 29 2006 Results for: 252x06031-002.MTW MTB > exec '252sols06031' Executing from file: 252sols06031.MTB Data Display K11 K12 K13 K14 K15 3.00000 4.00000 5.00000 6.00000 7.00000 Regression Analysis: pensioners versus year The regression equation is pensioners = 7.53 + 0.147 year Predictor Coef SE Coef T P Constant 7.53218 0.06530 115.35 0.000 year 0.146589 0.005395 27.17 0.000 S = 0.141872 R-Sq = 99.2% R-Sq(adj) = 99.1% Analysis of Variance Source DF SS Regression 1 14.859 Residual Error 6 0.121 Total 7 14.980 MS 14.859 0.020 F 738.25 P 0.000 Obs year pensioners Fit SE Fit Residual St Resid 1 -4.0 6.6790 6.9458 0.0808 -0.2668 -2.29R 2 1.0 7.6770 7.6788 0.0620 -0.0018 -0.01 3 5.0 8.3210 8.2651 0.0523 0.0559 0.42 4 6.0 8.5100 8.4117 0.0510 0.0983 0.74 5 7.0 8.6370 8.5583 0.0503 0.0787 0.59 6 8.0 8.7850 8.7049 0.0502 0.0801 0.60 7 9.0 8.9370 8.8515 0.0506 0.0855 0.65 8 30.0 11.8000 11.9299 0.1301 -0.1299 -2.30RX R denotes an observation with a large standardized residual. X denotes an observation whose X value gives it large influence. Predicted Values for New Observations New Obs Fit SE Fit 95% CI 1 11.9299 0.1301 (11.6115, 12.2482) 2 12.6628 0.1553 (12.2827, 13.0429) 3 12.8094 0.1605 (12.4168, 13.2020) 4 19.1127 0.3877 (18.1642, 20.0613) 5 19.2593 0.3930 (18.2977, 20.2210) 95% (11.4588, (12.1480, (12.2853, (18.1026, (18.2369, PI 12.4009)X 13.1776)X 13.3335)XX 20.1228)XX 20.2817)XX X denotes a point that is an outlier in the predictors. XX denotes a point that is an extreme outlier in the predictors. 9 251y0631s1 12/12/06 Values of Predictors for New Observations New Obs year 1 30.0 2 35.0 3 36.0 4 79.0 5 80.0 Data Display Row 1 2 3 4 5 6 7 8 year -4 1 5 6 7 8 9 30 pensioners 6.679 7.677 8.321 8.510 8.637 8.785 8.937 11.800 _xsq 16 1 25 36 49 64 81 900 _xy -26.716 7.677 41.605 51.060 60.459 70.280 80.433 354.000 _ysq 44.609 58.936 69.239 72.420 74.598 77.176 79.870 139.240 Data Display sum_y sum_x sum_xsq sum_xy sum_ysq 69.3460 62.0000 1172.00 638.798 616.088 Data Display _n _SSX _SSY _SSxy _xbar _ybar 8.00000 691.500 14.9800 101.367 7.75000 8.66825 10 251y0631s1 12/12/06 Take-Home Problem 1, Version 3 MTB > WOpen "C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06031003.MTW". Retrieving worksheet from file: 'C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06031-003.MTW' Worksheet was saved on Wed Nov 29 2006 Results for: 252x06031-003.MTW MTB > exec '252sols06031' Executing from file: 252sols06031.MTB Data Display K11 K12 K13 K14 K15 3.00000 4.00000 5.00000 6.00000 7.00000 Regression Analysis: pensioners versus year The regression equation is pensioners = 7.54 + 0.143 year Predictor Coef SE Coef T P Constant 7.54462 0.07237 104.25 0.000 year 0.143372 0.005979 23.98 0.000 S = 0.157230 R-Sq = 99.0% R-Sq(adj) = 98.8% Analysis of Variance Source DF SS Regression 1 14.214 Residual Error 6 0.148 Total 7 14.362 MS 14.214 0.025 F 574.97 P 0.000 Obs year pensioners Fit SE Fit Residual St Resid 1 -4.0 6.6790 6.9711 0.0896 -0.2921 -2.26R 2 1.0 7.6770 7.6880 0.0687 -0.0110 -0.08 3 5.0 8.3210 8.2615 0.0580 0.0595 0.41 4 6.0 8.5100 8.4048 0.0566 0.1052 0.72 5 7.0 8.6370 8.5482 0.0558 0.0888 0.60 6 8.0 8.7850 8.6916 0.0556 0.0934 0.64 7 9.0 8.9370 8.8350 0.0561 0.1020 0.69 8 30.0 11.7000 11.8458 0.1442 -0.1458 -2.32RX R denotes an observation with a large standardized residual. X denotes an observation whose X value gives it large influence. Predicted Values for New Observations New Obs Fit SE Fit 95% CI 95% PI 1 11.8458 0.1442 (11.4930, 12.1986) (11.3238, 12.3678)X 2 12.5626 0.1722 (12.1414, 12.9839) (11.9921, 13.1331)X 3 12.7060 0.1778 (12.2709, 13.1411) (12.1252, 13.2868)XX 4 18.8710 0.4296 (17.8197, 19.9222) (17.7515, 19.9904)XX 5 19.0144 0.4356 (17.9486, 20.0801) (17.8813, 20.1474)XX X denotes a point that is an outlier in the predictors. XX denotes a point that is an extreme outlier in the predictors. 11 251y0631s1 12/12/06 Values of Predictors for New Observations New Obs year 1 30.0 2 35.0 3 36.0 4 79.0 5 80.0 Data Display Row 1 2 3 4 5 6 7 8 year -4 1 5 6 7 8 9 30 pensioners 6.679 7.677 8.321 8.510 8.637 8.785 8.937 11.700 _xsq 16 1 25 36 49 64 81 900 _xy -26.716 7.677 41.605 51.060 60.459 70.280 80.433 351.000 _ysq 44.609 58.936 69.239 72.420 74.598 77.176 79.870 136.890 Data Display sum_y sum_x sum_xsq sum_xy sum_ysq 69.2460 62.0000 1172.00 635.798 613.738 Data Display _n _SSX _SSY _SSxy _xbar _ybar 8.00000 691.500 14.3624 99.1415 7.75000 8.65575 12 251y0631s1 12/12/06 Take-Home Problem 1, Version 4 MTB > WOpen "C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06031004.MTW". Retrieving worksheet from file: 'C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06031-004.MTW' Worksheet was saved on Wed Nov 29 2006 Results for: 252x06031-004.MTW MTB > exec '252sols06031' Executing from file: 252sols06031.MTB Data Display K11 K12 K13 K14 K15 3.00000 4.00000 5.00000 6.00000 7.00000 Regression Analysis: pensioners versus year The regression equation is pensioners = 7.56 + 0.140 year Predictor Coef SE Coef T Constant 7.55706 0.07952 95.04 year 0.140154 0.006570 21.33 S = 0.172759 R-Sq = 98.7% Analysis of Variance Source DF SS Regression 1 13.583 Residual Error 6 0.179 Total 7 13.762 P 0.000 0.000 R-Sq(adj) = 98.5% MS 13.583 0.030 F 455.12 P 0.000 Obs year pensioners Fit SE Fit Residual St Resid 1 -4.0 6.6790 6.9964 0.0984 -0.3174 -2.24R 2 1.0 7.6770 7.6972 0.0755 -0.0202 -0.13 3 5.0 8.3210 8.2578 0.0637 0.0632 0.39 4 6.0 8.5100 8.3980 0.0622 0.1120 0.69 5 7.0 8.6370 8.5381 0.0613 0.0989 0.61 6 8.0 8.7850 8.6783 0.0611 0.1067 0.66 7 9.0 8.9370 8.8184 0.0616 0.1186 0.73 8 30.0 11.6000 11.7617 0.1584 -0.1617 -2.35RX R denotes an observation with a large standardized residual. X denotes an observation whose X value gives it large influence. Predicted Values for New Observations New Obs Fit SE Fit 95% CI 95% PI 1 11.7617 0.1584 (11.3740, 12.1493) (11.1881, 12.3352)X 2 12.4624 0.1892 (11.9996, 12.9253) (11.8356, 13.0893)X 3 12.6026 0.1954 (12.1245, 13.0807) (11.9644, 13.2408)XX 4 18.6292 0.4721 (17.4741, 19.7843) (17.3992, 19.8592)XX 5 18.7694 0.4786 (17.5984, 19.9404) (17.5244, 20.0144)XX X denotes a point that is an outlier in the predictors. XX denotes a point that is an extreme outlier in the predictors. 13 251y0631s1 12/12/06 Values of Predictors for New Observations New Obs year 1 30.0 2 35.0 3 36.0 4 79.0 5 80.0 Data Display Row 1 2 3 4 5 6 7 8 year -4 1 5 6 7 8 9 30 pensioners 6.679 7.677 8.321 8.510 8.637 8.785 8.937 11.600 _xsq 16 1 25 36 49 64 81 900 _xy -26.716 7.677 41.605 51.060 60.459 70.280 80.433 348.000 _ysq 44.609 58.936 69.239 72.420 74.598 77.176 79.870 134.560 Data Display sum_y sum_x sum_xsq sum_xy sum_ysq 69.1460 62.0000 1172.00 632.798 611.408 Data Display _n _SSX _SSY _SSxy _xbar _ybar 8.00000 691.500 13.7623 96.9165 7.75000 8.64325 14 251y0631s1 12/12/06 Take-Home Problem 1, Version 5 MTB > WOpen "C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06031005.MTW". Retrieving worksheet from file: 'C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06031-005.MTW' Worksheet was saved on Wed Nov 29 2006 Results for: 252x06031-005.MTW MTB > exec '252sols06031' Executing from file: 252sols06031.MTB Data Display K11 K12 K13 K14 K15 3.00000 4.00000 5.00000 6.00000 7.00000 Regression Analysis: pensioners versus year The regression equation is pensioners = 7.57 + 0.137 year Predictor Coef SE Coef T P Constant 7.56949 0.08672 87.28 0.000 year 0.136936 0.007165 19.11 0.000 S = 0.188414 R-Sq = 98.4% R-Sq(adj) = 98.1% Analysis of Variance Source DF SS Regression 1 12.967 Residual Error 6 0.213 Total 7 13.180 MS 12.967 0.035 F 365.26 P 0.000 Obs year pensioners Fit SE Fit Residual St Resid 1 -4.0 6.6790 7.0217 0.1074 -0.3427 -2.21R 2 1.0 7.6770 7.7064 0.0823 -0.0294 -0.17 3 5.0 8.3210 8.2542 0.0695 0.0668 0.38 4 6.0 8.5100 8.3911 0.0678 0.1189 0.68 5 7.0 8.6370 8.5280 0.0668 0.1090 0.62 6 8.0 8.7850 8.6650 0.0666 0.1200 0.68 7 9.0 8.9370 8.8019 0.0672 0.1351 0.77 8 30.0 11.5000 11.6776 0.1728 -0.1776 -2.36RX R denotes an observation with a large standardized residual. X denotes an observation whose X value gives it large influence. Predicted Values for New Observations New Obs Fit SE Fit 95% CI 95% PI 1 11.6776 0.1728 (11.2548, 12.1004) (11.0521, 12.3031)X 2 12.3623 0.2063 (11.8575, 12.8671) (11.6786, 13.0459)X 3 12.4992 0.2131 (11.9778, 13.0206) (11.8032, 13.1952)XX 4 18.3875 0.5148 (17.1277, 19.6472) (17.0460, 19.7289)XX 5 18.5244 0.5219 (17.2473, 19.8015) (17.1666, 19.8822)XX X denotes a point that is an outlier in the predictors. XX denotes a point that is an extreme outlier in the predictors. 15 251y0631s1 12/12/06 Values of Predictors for New Observations New Obs year 1 30.0 2 35.0 3 36.0 4 79.0 5 80.0 Data Display Row 1 2 3 4 5 6 7 8 year -4 1 5 6 7 8 9 30 pensioners 6.679 7.677 8.321 8.510 8.637 8.785 8.937 11.500 _xsq 16 1 25 36 49 64 81 900 _xy -26.716 7.677 41.605 51.060 60.459 70.280 80.433 345.000 _ysq 44.609 58.936 69.239 72.420 74.598 77.176 79.870 132.250 Data Display sum_y sum_x sum_xsq sum_xy sum_ysq 69.0460 62.0000 1172.00 629.798 609.098 Data Display _n _SSX _SSY _SSxy _xbar _ybar 8.00000 691.500 13.1797 94.6915 7.75000 8.63075 16 251y0631s1 12/12/06 Take-Home Problem 1, Version 6 MTB > WOpen "C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06031006.MTW". Retrieving worksheet from file: 'C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06031-006.MTW' Worksheet was saved on Wed Nov 29 2006 Results for: 252x06031-006.MTW MTB > exec '252sols06031' Executing from file: 252sols06031.MTB Data Display K11 K12 K13 K14 K15 3.00000 4.00000 5.00000 6.00000 7.00000 Regression Analysis: pensioners versus year The regression equation is pensioners = 7.58 + 0.134 year Predictor Coef SE Coef T Constant 7.58193 0.09397 80.68 year 0.133719 0.007764 17.22 S = 0.204168 R-Sq = 98.0% Analysis of Variance Source DF SS Regression 1 12.365 Residual Error 6 0.250 Total 7 12.615 P 0.000 0.000 R-Sq(adj) = 97.7% MS 12.365 0.042 F 296.62 P 0.000 Obs year pensioners Fit SE Fit Residual St Resid 1 -4.0 6.6790 7.0471 0.1163 -0.3681 -2.19R 2 1.0 7.6770 7.7156 0.0892 -0.0386 -0.21 3 5.0 8.3210 8.2505 0.0753 0.0705 0.37 4 6.0 8.5100 8.3842 0.0735 0.1258 0.66 5 7.0 8.6370 8.5180 0.0724 0.1190 0.62 6 8.0 8.7850 8.6517 0.0722 0.1333 0.70 7 9.0 8.9370 8.7854 0.0728 0.1516 0.79 8 30.0 11.4000 11.5935 0.1872 -0.1935 -2.38RX R denotes an observation with a large standardized residual. X denotes an observation whose X value gives it large influence. Predicted Values for New Observations New Obs Fit SE Fit 95% CI 1 11.5935 0.1872 (11.1354, 12.0516) 2 12.2621 0.2235 (11.7151, 12.8091) 3 12.3958 0.2309 (11.8308, 12.9608) 4 18.1457 0.5579 (16.7806, 19.5108) 5 18.2794 0.5656 (16.8955, 19.6634) 95% (10.9157, (11.5213, (11.6416, (16.6921, (16.8081, PI 12.2713)X 13.0029)X 13.1500)XX 19.5993)XX 19.7508)XX X denotes a point that is an outlier in the predictors. XX denotes a point that is an extreme outlier in the predictors. 17 251y0631s1 12/12/06 Values of Predictors for New Observations New Obs 1 2 3 4 5 year 30.0 35.0 36.0 79.0 80.0 Data Display Row 1 2 3 4 5 6 7 8 year -4 1 5 6 7 8 9 30 pensioners 6.679 7.677 8.321 8.510 8.637 8.785 8.937 11.400 _xsq 16 1 25 36 49 64 81 900 _xy -26.716 7.677 41.605 51.060 60.459 70.280 80.433 342.000 _ysq 44.609 58.936 69.239 72.420 74.598 77.176 79.870 129.960 Data Display sum_y sum_x sum_xsq sum_xy sum_ysq 68.9460 62.0000 1172.00 626.798 606.808 Data Display _n _SSX _SSY _SSxy _xbar _ybar 8.00000 691.500 12.6146 92.4665 7.75000 8.61825 18 251y0631s1 12/12/06 Take-Home Problem 1, Version 7 MTB > WOpen "C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06031007.MTW". Retrieving worksheet from file: 'C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06031-007.MTW' Worksheet was saved on Wed Nov 29 2006 Results for: 252x06031-007.MTW MTB > exec '252sols06031' Executing from file: 252sols06031.MTB Data Display K11 K12 K13 K14 K15 3.00000 4.00000 5.00000 6.00000 7.00000 Regression Analysis: pensioners versus year The regression equation is pensioners = 7.59 + 0.131 year Predictor Constant year Coef 7.5944 0.130501 S = 0.219998 SE Coef 0.1013 0.008366 R-Sq = 97.6% Analysis of Variance Source DF SS Regression 1 11.777 Residual Error 6 0.290 Total 7 12.067 T 75.00 15.60 P 0.000 0.000 R-Sq(adj) = 97.2% MS 11.777 0.048 F 243.32 P 0.000 Obs year pensioners Fit SE Fit Residual St Resid 1 -4.0 6.6790 7.0724 0.1254 -0.3934 -2.18R 2 1.0 7.6770 7.7249 0.0961 -0.0479 -0.24 3 5.0 8.3210 8.2469 0.0811 0.0741 0.36 4 6.0 8.5100 8.3774 0.0791 0.1326 0.65 5 7.0 8.6370 8.5079 0.0780 0.1291 0.63 6 8.0 8.7850 8.6384 0.0778 0.1466 0.71 7 9.0 8.9370 8.7689 0.0785 0.1681 0.82 8 30.0 11.3000 11.5094 0.2017 -0.2094 -2.39RX R denotes an observation with a large standardized residual. X denotes an observation whose X value gives it large influence. Predicted Values for New Observations New Obs Fit SE Fit 95% CI 95% PI 1 11.5094 0.2017 (11.0158, 12.0030) (10.7790, 12.2398)X 2 12.1619 0.2409 (11.5725, 12.7513) (11.3637, 12.9601)X 3 12.2924 0.2488 (11.6836, 12.9012) (11.4797, 13.1051)XX 4 17.9040 0.6011 (16.4330, 19.3749) (16.3376, 19.4703)XX 5 18.0345 0.6094 (16.5432, 19.5257) (16.4490, 19.6199)XX X denotes a point that is an outlier in the predictors. XX denotes a point that is an extreme outlier in the predictors. 19 251y0631s1 12/12/06 Values of Predictors for New Observations New Obs year 1 30.0 2 35.0 3 36.0 4 79.0 5 80.0 Data Display Row 1 2 3 4 5 6 7 8 year -4 1 5 6 7 8 9 30 pensioners 6.679 7.677 8.321 8.510 8.637 8.785 8.937 11.300 _xsq 16 1 25 36 49 64 81 900 _xy -26.716 7.677 41.605 51.060 60.459 70.280 80.433 339.000 _ysq 44.609 58.936 69.239 72.420 74.598 77.176 79.870 127.690 Data Display sum_y sum_x sum_xsq sum_xy sum_ysq 68.8460 62.0000 1172.00 623.798 604.538 Data Display _n _SSX _SSY _SSxy _xbar _ybar 8.00000 691.500 12.0670 90.2415 7.75000 8.60575 20 251y0631s1 12/12/06 Take-Home Problem 1, Version 8 MTB > WOpen "C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06031008.MTW". Retrieving worksheet from file: 'C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06031-008.MTW' Worksheet was saved on Wed Nov 29 2006 Results for: 252x06031-008.MTW MTB > exec '252sols06031' Executing from file: 252sols06031.MTB Data Display K11 K12 K13 K14 K15 3.00000 4.00000 5.00000 6.00000 7.00000 Regression Analysis: pensioners versus year The regression equation is pensioners = 7.61 + 0.127 year Predictor Constant year Coef 7.6068 0.127283 S = 0.235891 SE Coef 0.1086 0.008970 R-Sq = 97.1% Analysis of Variance Source DF SS Regression 1 11.203 Residual Error 6 0.334 Total 7 11.537 Obs 1 2 3 4 5 6 7 8 year -4.0 1.0 5.0 6.0 7.0 8.0 9.0 30.0 pensioners 6.6790 7.6770 8.3210 8.5100 8.6370 8.7850 8.9370 11.2000 T 70.06 14.19 P 0.000 0.000 R-Sq(adj) = 96.6% MS 11.203 0.056 Fit 7.0977 7.7341 8.2432 8.3705 8.4978 8.6251 8.7524 11.4253 F 201.33 SE Fit 0.1344 0.1031 0.0870 0.0849 0.0837 0.0834 0.0842 0.2163 P 0.000 Residual -0.4187 -0.0571 0.0778 0.1395 0.1392 0.1599 0.1846 -0.2253 St Resid -2.16R -0.27 0.35 0.63 0.63 0.72 0.84 -2.39RX R denotes an observation with a large standardized residual. X denotes an observation whose X value gives it large influence. Predicted Values for New Observations New Obs 1 2 3 4 5 Fit 11.4253 12.0617 12.1890 17.6622 17.7895 SE Fit 0.2163 0.2583 0.2668 0.6446 0.6535 95% (10.8960, (11.4297, (11.5362, (16.0850, (16.1905, CI 11.9546) 12.6937) 12.8418) 19.2394) 19.3884) 95% (10.6422, (11.2058, (11.3176, (15.9827, (16.0895, PI 12.2085)X 12.9176)X 13.0604)XX 19.3417)XX 19.4894)XX X denotes a point that is an outlier in the predictors. XX denotes a point that is an extreme outlier in the predictors. 21 251y0631s1 12/12/06 Values of Predictors for New Observations New Obs year 1 30.0 2 35.0 3 36.0 4 79.0 5 80.0 Data Display Row 1 2 3 4 5 6 7 8 year -4 1 5 6 7 8 9 30 pensioners 6.679 7.677 8.321 8.510 8.637 8.785 8.937 11.200 _xsq 16 1 25 36 49 64 81 900 _xy -26.716 7.677 41.605 51.060 60.459 70.280 80.433 336.000 _ysq 44.609 58.936 69.239 72.420 74.598 77.176 79.870 125.440 Data Display sum_y sum_x sum_xsq sum_xy sum_ysq 68.7460 62.0000 1172.00 620.798 602.288 Data Display _n _SSX _SSY _SSxy _xbar _ybar 8.00000 691.500 11.5369 88.0165 7.75000 8.59325 22 251y0631s1 12/12/06 Take-Home Problem 1, Version 9 MTB > WOpen "C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06031009.MTW". Retrieving worksheet from file: 'C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06031-009.MTW' Worksheet was saved on Wed Nov 29 2006 Results for: 252x06031-009.MTW MTB > exec '252sols06031' Executing from file: 252sols06031.MTB Data Display K11 K12 K13 K14 K15 3.00000 4.00000 5.00000 6.00000 7.00000 Regression Analysis: pensioners versus year The regression equation is pensioners = 7.62 + 0.124 year Predictor Constant year Coef 7.6192 0.124066 S = 0.251833 SE Coef 0.1159 0.009577 R-Sq = 96.5% Analysis of Variance Source DF SS Regression 1 10.644 Residual Error 6 0.381 Total 7 11.024 T 65.73 12.95 P 0.000 0.000 R-Sq(adj) = 96.0% MS 10.644 0.063 F 167.83 P 0.000 Obs year pensioners Fit SE Fit Residual St Resid 1 -4.0 6.6790 7.1230 0.1435 -0.4440 -2.15R 2 1.0 7.6770 7.7433 0.1100 -0.0663 -0.29 3 5.0 8.3210 8.2396 0.0928 0.0814 0.35 4 6.0 8.5100 8.3636 0.0906 0.1464 0.62 5 7.0 8.6370 8.4877 0.0893 0.1493 0.63 6 8.0 8.7850 8.6118 0.0891 0.1732 0.74 7 9.0 8.9370 8.7358 0.0898 0.2012 0.86 8 30.0 11.1000 11.3412 0.2309 -0.2412 -2.40RX R denotes an observation with a large standardized residual. X denotes an observation whose X value gives it large influence. Predicted Values for New Observations New Obs Fit SE Fit 95% CI 95% PI 1 11.3412 0.2309 (10.7761, 11.9063) (10.5051, 12.1773)X 2 11.9615 0.2757 (11.2868, 12.6362) (11.0478, 12.8753)X 3 12.0856 0.2848 (11.3887, 12.7825) (11.1553, 13.0159)XX 4 17.4204 0.6881 (15.7367, 19.1042) (15.6274, 19.2134)XX 5 17.5445 0.6976 (15.8375, 19.2515) (15.7297, 19.3593)XX X denotes a point that is an outlier in the predictors. XX denotes a point that is an extreme outlier in the predictors. 23 251y0631s1 12/12/06 Values of Predictors for New Observations New Obs year 1 30.0 2 35.0 3 36.0 4 79.0 5 80.0 Data Display Row 1 2 3 4 5 6 7 8 year -4 1 5 6 7 8 9 30 pensioners 6.679 7.677 8.321 8.510 8.637 8.785 8.937 11.100 _xsq 16 1 25 36 49 64 81 900 _xy -26.716 7.677 41.605 51.060 60.459 70.280 80.433 333.000 _ysq 44.609 58.936 69.239 72.420 74.598 77.176 79.870 123.210 Data Display sum_y sum_x sum_xsq sum_xy sum_ysq 68.6460 62.0000 1172.00 617.798 600.058 Data Display _n _SSX _SSY _SSxy _xbar _ybar 8.00000 691.500 11.0243 85.7915 7.75000 8.58075 24 251y0631s1 12/12/06 2) The Lees in their text ask whether experience makes a difference in student earnings and present the following data for student earnings versus years of work experience. To personalize these data, take the second to last digit of your student number call it a . Clearly label the problem with a version number based on your student number. Then take your a , multiply it by 0.5 and add it to the 13 in the lower left corner. . (Example: Good ol’ Seymour’s student number is 123456, so the 13 becomes 13 + 0.5(5) = 13 + 2.5 = 15.5 and he labels it Version 5.) Each column is to be regarded as an independent random sample. Years of Work Experience 1 2 3 16 19 24 21 20 21 18 21 22 13 20 25 a) State your null hypothesis and test it by doing a 1-way ANOVA on these data and explain whether the test tells us that experience matters or not. (4) b) Using your results from a) present two different confidence intervals for the difference between earnings for those with 1 and 3 years experience. Explain (i) under what circumstances you would use each interval and (ii) whether the intervals show a significant difference. (2) c) What other method could we use on these data to see if years of experience make a difference? Under what circumstances would we use it? Try it and tell what it tests and what it shows. (3) [24] d) (Extra Credit) Do a Levene test on these data and explain what it tests and shows. (4) You should be able to do the calculations below. Only the three columns of numbers were given to us. 1 16 21 18 13 Years 2 19 20 21 20 3 24 20 22 25 Sum 68 + 80 + 92 240 nj 4+ 4+ 4 12 n x j 17 20 23 SS 1190 + 1602 + 2126 x 2j 289 400 + x nx 49181220 SSB n x nx 417 420 SST 2 ij 2 j .j Source Between 2 2 2 SS 72 Sum x 20 x x 1218 x 4918 4918 4800 118 2 4232 12202 41218 12202 4872 4800 72 2 2 ij 2 j 529 2 DF ij MS 36 F F.05 7.04 s F 2,9 4.26 H0 Column means equal Within 46 9 5.1111 Total 118 11 Because our computed F statistic exceeds the 5% table value, we reject the null hypothesis of equal means and conclude that experience matters. b) The following material is modified from the solution to the last graded assignment. Types of contrast between means. Assume 0.05 . m 4 is the number of columns. 25 251y0631s1 12/12/06 Individual Confidence Interval If we desire a single interval, we use the formula for the difference between two means when the variance is known. For example, if we want the difference between means of column 1 and column 2. 1 2 x1 x2 tn m s 2 1 1 , where s MSW . The within degrees of freedom are n1 n2 9 2.262 . n1 n 2 n3 n4 4 , so n m 9, , so we use t .025 s2 1 n1 1 n2 s 2 1 4 1 4 s 2 0.5 and our interval will be 1 3 x1 x3 2.262 s 2 .5 Scheffé e Confidence Interval If we desire intervals that will simultaneously be valid for a given confidence level for all possible intervals 1 1 between column means, use 1 2 x1 x2 m 1Fm1,n m s where s MSW . n n 2 1 The degrees of freedom for columns are m 1 2 . The within degrees of freedom are n m 9, so we 2,9 4.26 . use F.05 n1 n 2 n3 n4 4 , so s2 1 n1 1 n2 s 2 18 18 s 2 0.25 and our interval will be 1 3 x1 x3 24.26 s 2 .5 x1 x2 2.9289 s 2 .5 Tukey Confidence Interval This also applies to all possible differences. 1 2 x1 x2 q m,n m s 1 1 . where s MSW . This gives rise to Tukey’s HSD n1 n 2 2 (Honestly Significant Difference) procedure. Two sample means x .1 and x .2 are significantly different if x.1 x.2 is greater than q m,n m s 2 1 1 n1 n 2 s 2 1 1 3,9 3,9 3.95 . . We will need q .05 . The table says q.05 n1 n 2 s 1 1 2 2 .25 s and the interval will be 1 3 x1 x3 3.95 0.5s .5 2 4 4 2 x1 x2 2.7931 s 2 .25 Contrasts for 3 and 1 . Note that in all contrasts s 2 .5 .5.1111 .5 2.555556 1.5986 . Intervals for differences between means that include zero show no significant difference. x1 x3 17 23 6. Individual – Used when you want only one interval. 1 3 x1 x3 2.262 s 2 .5 6 2.262 1.5986 6 3.61 Scheffé – Used when a collective confidence level is sought. 1 3 x1 x2 2.9289 s 2 .5 6 2.9289 1.5986 6 4.68 Tukey – More powerful, but similar to the Scheffé. 1 3 x1 x2 2.7931 s 2 .25 6 2.7931 1.5986 6 4.47 . All contrasts seem significant. 26 251y0631s1 12/12/06 c) The alternative to one-way ANOVA for situations in which the parent distribution is not Normal is the 2.0 4.0 11 .0 16 19 24 8 .0 5 .5 8 .0 21 20 21 Kruskal-Wallis test. The original data is replaced by ranks 3.0 8.0 10 .0 . Note that the 18 21 22 1.0 5.5 12 .0 13 20 25 14 .0 23 .0 41 .0 12 13 78 , so that we can check our ranking by noting that 14 + 23 + 2 SRi 2 3n 1 n i sum of the first twelve numbers is 12 41 = 78. H nn 1 i 12 14 2 23 2 412 313 1 1 196 529 1681 39 46 .2692 39 7.2692 . Since the 12 13 4 4 4 13 4 Kruskal-Wallis table for 4, 4, 4 says that 5.6923 has a p-value of .049 and 7.5385 has a p-value of .011, the p-value of 7.2692 must be below 5%, so that we can reject the null hypothesis of equal medians. 16 19 24 21 20 21 , which has column medians 18 21 22 13 20 25 1 1 1 4 0 2 of 17, 20 and 23, is replaced by the numbers with the column medians subtracted . Absolute 1 1 1 4 0 2 1 1 1 4 0 2 values are taken, so the columns become . An ANOVA is done on these 3 columns. 1 1 1 4 0 2 Source SS DF MS F.05 H0 F d) The Levene test is a test for equal variances. The original data Between 8 2 4 3.27 ns F 2,9 4.26 Column means equal Within 11 9 1.2222 Total 19 11 Because we cannot reject the null hypothesis, we cannot say that the variances are not equal. ————— 12/1/2006 12:23:02 AM ———————————————————— Welcome to Minitab, press F1 for help. 27 251y0631s1 12/12/06 Take-Home Problem 2, Version 0 MTB > WOpen "C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06032000.MTW". Retrieving worksheet from file: 'C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06032-000.MTW' Worksheet was saved on Thu Nov 30 2006 Results for: 252x06032-000.MTW MTB > Execute "C:\Documents and Settings\RBOVE\My Documents\Minitab\252oneW306032.mtb" 1. Executing from file: C:\Documents and Settings\RBOVE\My Documents\Minitab\252oneW306032.mtb Executing from file: 2522onw3.MTB One-way ANOVA: 1, 2, 3 Source DF Factor 2 Error 9 Total 11 S = 2.261 Level 1 2 3 N 4 4 4 SS MS 72.00 36.00 46.00 5.11 118.00 R-Sq = 61.02% Mean 17.000 20.000 23.000 StDev 3.367 0.816 1.826 F 7.04 P 0.014 R-Sq(adj) = 52.35% Individual 95% CIs For Mean Based on Pooled StDev --+---------+---------+---------+------(--------*-------) (--------*-------) (--------*-------) --+---------+---------+---------+------15.0 18.0 21.0 24.0 Pooled StDev = 2.261 Data Display Row 1 2 3 4 1 16 21 18 13 2 19 20 21 20 3 24 21 22 25 Data Display Row 1 2 3 4 x1sq 256 441 324 169 x2sq 361 400 441 400 x3sq 576 441 484 625 Data Display sumx1 sumx2 sumx3 n1 n2 n3 smx1sq smx2sq smx3sq 68.0000 80.0000 92.0000 4.00000 4.00000 4.00000 1190.00 1602.00 2126.00 Data Display x1bar x2bar x3bar 17.0000 20.0000 23.0000 28 251y0631s1 12/12/06 Data Display Row 1 2 3 4 r1 2 8 3 1 r2 4.0 5.5 8.0 5.5 r3 11 8 10 12 Kruskal-Wallis Test: C11 versus C12 Kruskal-Wallis Test on C11 C12 N Median Ave Rank 1 4 17.00 3.5 2 4 20.00 5.8 3 4 23.00 10.3 Overall 12 6.5 Z -2.04 -0.51 2.55 H = 7.27 DF = 2 P = 0.026 H = 7.40 DF = 2 P = 0.025 (adjusted for ties) * NOTE * One or more small samples Test for Equal Variances: C11 versus C12 95% Bonferroni confidence intervals for standard deviations C12 N Lower StDev Upper 1 4 1.70187 3.36650 18.3097 2 4 0.41276 0.81650 4.4408 3 4 0.92297 1.82574 9.9298 Bartlett's Test (normal distribution) Test statistic = 4.36, p-value = 0.113 Levene's Test (any continuous distribution) Test statistic = 3.27, p-value = 0.085 Test for Equal Variances: C11 versus C12 Executing from file: 252Levene3.MTB Data Display Row 1 2 3 4 C21 16 21 18 13 C22 19 20 21 20 C23 24 21 22 25 Data Display median1 median2 median3 17.0000 20.0000 23.0000 Data Display Row 1 2 3 4 C21 -1 4 1 -4 C22 -1 0 1 0 C23 1 -2 -1 2 Data Display Row 1 2 3 4 C21 1 4 1 4 C22 1 0 1 0 C23 1 2 1 2 29 251y0631s1 12/12/06 One-way ANOVA: C21, C22, C23 Source DF Factor 2 Error 9 Total 11 S = 1.106 Level C21 C22 C23 N 4 4 4 SS MS F P 8.00 4.00 3.27 0.085 11.00 1.22 19.00 R-Sq = 42.11% R-Sq(adj) = 29.24% Mean 2.500 0.500 1.500 StDev 1.732 0.577 0.577 Individual 95% CIs For Mean Based on Pooled StDev ------+---------+---------+---------+--(----------*---------) (---------*----------) (----------*---------) ------+---------+---------+---------+--0.0 1.2 2.4 3.6 Pooled StDev = 1.106 30 251y0631s1 12/12/06 Take-Home Problem 2, Version 1 MTB > WOpen "C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06032001.MTW". Retrieving worksheet from file: 'C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06032-001.MTW' Worksheet was saved on Thu Nov 30 2006 Results for: 252x06032-001.MTW MTB > exec '252oneW306032' Executing from file: 252oneW306032.MTB Executing from file: 2522onw3.MTB One-way ANOVA: 1, 2, 3 Source DF Factor 2 Error 9 Total 11 S = 2.165 Level 1 2 3 N 4 4 4 SS MS 69.04 34.52 42.19 4.69 111.23 R-Sq = 62.07% Mean 17.125 20.000 23.000 StDev 3.172 0.816 1.826 F 7.36 P 0.013 R-Sq(adj) = 53.64% Individual 95% CIs For Mean Based on Pooled StDev -+---------+---------+---------+-------(-------*-------) (-------*-------) (-------*-------) -+---------+---------+---------+-------15.0 18.0 21.0 24.0 Pooled StDev = 2.165 Data Display Row 1 2 3 4 1 16.0 21.0 18.0 13.5 2 19 20 21 20 3 24 21 22 25 Data Display Row 1 2 3 4 x1sq 256.00 441.00 324.00 182.25 x2sq 361 400 441 400 x3sq 576 441 484 625 Data Display sumx1 sumx2 sumx3 n1 n2 n3 smx1sq smx2sq smx3sq 68.5000 80.0000 92.0000 4.00000 4.00000 4.00000 1203.25 1602.00 2126.00 Data Display x1bar x2bar x3bar 17.1250 20.0000 23.0000 31 251y0631s1 12/12/06 Data Display Row 1 2 3 4 r1 2 8 3 1 r2 4.0 5.5 8.0 5.5 r3 11 8 10 12 Kruskal-Wallis Test: C11 versus C12 Kruskal-Wallis Test on C11 C12 N Median Ave Rank Z 1 4 17.00 3.5 -2.04 2 4 20.00 5.8 -0.51 3 4 23.00 10.3 2.55 Overall 12 6.5 H = 7.27 DF = 2 P = 0.026 H = 7.40 DF = 2 P = 0.025 (adjusted for ties) * NOTE * One or more small samples Test for Equal Variances: C11 versus C12 95% Bonferroni confidence intervals for standard deviations C12 1 2 3 N 4 4 4 Lower 1.60362 0.41276 0.92297 StDev 3.17214 0.81650 1.82574 Upper 17.2526 4.4408 9.9298 Bartlett's Test (normal distribution) Test statistic = 3.99, p-value = 0.136 Levene's Test (any continuous distribution) Test statistic = 3.27, p-value = 0.086 Test for Equal Variances: C11 versus C12 Executing from file: 252Levene3.MTB Data Display Row 1 2 3 4 C21 16.0 21.0 18.0 13.5 C22 19 20 21 20 C23 24 21 22 25 Data Display median1 median2 median3 17.0000 20.0000 23.0000 Data Display Row 1 2 3 4 C21 -1.0 4.0 1.0 -3.5 C22 -1 0 1 0 C23 1 -2 -1 2 Data Display Row 1 2 3 4 C21 1.0 4.0 1.0 3.5 C22 1 0 1 0 C23 1 2 1 2 32 251y0631s1 12/12/06 One-way ANOVA: C21, C22, C23 Source DF Factor 2 Error 9 Total 11 S = 1.037 Level C21 C22 C23 N 4 4 4 SS MS F P 7.04 3.52 3.27 0.086 9.69 1.08 16.73 R-Sq = 42.09% R-Sq(adj) = 29.22% Mean 2.375 0.500 1.500 StDev 1.601 0.577 0.577 Individual 95% CIs For Mean Based on Pooled StDev ------+---------+---------+---------+--(---------*---------) (---------*---------) (---------*--------) ------+---------+---------+---------+--0.0 1.2 2.4 3.6 Pooled StDev = 1.037 33 251y0631s1 12/12/06 Take-Home Problem 2, Version 2 MTB > WOpen "C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06032002.MTW". Retrieving worksheet from file: 'C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06032-002.MTW' Worksheet was saved on Thu Nov 30 2006 Results for: 252x06032-002.MTW MTB > exec '252oneW306032' Executing from file: 252oneW306032.MTB Executing from file: 2522onw3.MTB One-way ANOVA: 1, 2, 3 Source DF Factor 2 Error 9 Total 11 S = 2.075 Level 1 2 3 N 4 4 4 SS MS 66.17 33.08 38.75 4.31 104.92 R-Sq = 63.07% Mean 17.250 20.000 23.000 StDev 2.986 0.816 1.826 F 7.68 P 0.011 R-Sq(adj) = 54.86% Individual 95% CIs For Mean Based on Pooled StDev +---------+---------+---------+--------(-------*------) (-------*------) (-------*------) +---------+---------+---------+--------15.0 18.0 21.0 24.0 Pooled StDev = 2.075 Data Display Row 1 2 3 4 1 16 21 18 14 2 19 20 21 20 3 24 21 22 25 Data Display Row 1 2 3 4 x1sq 256 441 324 196 x2sq 361 400 441 400 x3sq 576 441 484 625 Data Display sumx1 sumx2 sumx3 n1 n2 n3 smx1sq smx2sq smx3sq 69.0000 80.0000 92.0000 4.00000 4.00000 4.00000 1217.00 1602.00 2126.00 Data Display x1bar x2bar x3bar 17.2500 20.0000 23.0000 34 251y0631s1 12/12/06 Data Display Row 1 2 3 4 r1 2 8 3 1 r2 4.0 5.5 8.0 5.5 r3 11 8 10 12 Kruskal-Wallis Test: C11 versus C12 Kruskal-Wallis Test on C11 C12 N Median Ave Rank Z 1 4 17.00 3.5 -2.04 2 4 20.00 5.8 -0.51 3 4 23.00 10.3 2.55 Overall 12 6.5 H = 7.27 DF = 2 P = 0.026 H = 7.40 DF = 2 P = 0.025 (adjusted for ties) * NOTE * One or more small samples Test for Equal Variances: C11 versus C12 95% Bonferroni confidence intervals for standard deviations C12 N Lower StDev Upper 1 4 1.50955 2.98608 16.2407 2 4 0.41276 0.81650 4.4408 3 4 0.92297 1.82574 9.9298 Bartlett's Test (normal distribution) Test statistic = 3.64, p-value = 0.162 Levene's Test (any continuous distribution) Test statistic = 3.17, p-value = 0.091 Test for Equal Variances: C11 versus C12 Executing from file: 252Levene3.MTB Data Display Row 1 2 3 4 C21 16 21 18 14 C22 19 20 21 20 C23 24 21 22 25 Data Display median1 median2 median3 17.0000 20.0000 23.0000 Data Display Row 1 2 3 4 C21 -1 4 1 -3 C22 -1 0 1 0 C23 1 -2 -1 2 Data Display Row 1 2 3 4 C21 1 4 1 3 C22 1 0 1 0 C23 1 2 1 2 35 251y0631s1 12/12/06 One-way ANOVA: C21, C22, C23 Source DF Factor 2 Error 9 Total 11 S = 0.9860 Level C21 C22 C23 N 4 4 4 SS MS F P 6.167 3.083 3.17 0.091 8.750 0.972 14.917 R-Sq = 41.34% R-Sq(adj) = 28.31% Mean 2.2500 0.5000 1.5000 StDev 1.5000 0.5774 0.5774 Individual 95% CIs For Mean Based on Pooled StDev ------+---------+---------+---------+--(----------*-----------) (----------*----------) (----------*----------) ------+---------+---------+---------+--0.0 1.0 2.0 3.0 Pooled StDev = 0.9860 36 251y0631s1 12/12/06 Take-Home Problem 2, Version 3 MTB > WOpen "C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06032003.MTW". Retrieving worksheet from file: 'C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06032-003.MTW' Worksheet was saved on Thu Nov 30 2006 Results for: 252x06032-003.MTW MTB > exec '252oneW306032' Executing from file: 252oneW306032.MTB Executing from file: 2522onw3.MTB One-way ANOVA: 1, 2, 3 Source DF Factor 2 Error 9 Total 11 S = 1.991 Level 1 2 3 N 4 4 4 SS MS F P 63.38 31.69 7.99 0.010 35.69 3.97 99.06 R-Sq = 63.97% R-Sq(adj) = 55.97% Mean 17.375 20.000 23.000 StDev 2.810 0.816 1.826 Individual 95% CIs For Mean Based on Pooled StDev +---------+---------+---------+--------(-------*------) (-------*------) (-------*------) +---------+---------+---------+--------15.0 18.0 21.0 24.0 Pooled StDev = 1.991 Data Display Row 1 2 3 4 1 16.0 21.0 18.0 14.5 2 19 20 21 20 3 24 21 22 25 Data Display Row 1 2 3 4 x1sq 256.00 441.00 324.00 210.25 x2sq 361 400 441 400 x3sq 576 441 484 625 Data Display sumx1 sumx2 sumx3 n1 n2 n3 smx1sq smx2sq smx3sq 69.5000 80.0000 92.0000 4.00000 4.00000 4.00000 1231.25 1602.00 2126.00 Data Display x1bar x2bar x3bar 17.3750 20.0000 23.0000 37 251y0631s1 12/12/06 Data Display Row 1 2 3 4 r1 2 8 3 1 r2 4.0 5.5 8.0 5.5 r3 11 8 10 12 Kruskal-Wallis Test: C11 versus C12 Kruskal-Wallis Test on C11 C12 N Median Ave Rank Z 1 4 17.00 3.5 -2.04 2 4 20.00 5.8 -0.51 3 4 23.00 10.3 2.55 Overall 12 6.5 H = 7.27 DF = 2 P = 0.026 H = 7.40 DF = 2 P = 0.025 (adjusted for ties) * NOTE * One or more small samples Test for Equal Variances: C11 versus C12 95% Bonferroni confidence intervals for standard deviations C12 N Lower StDev Upper 1 4 1.42052 2.80995 15.2827 2 4 0.41276 0.81650 4.4408 3 4 0.92297 1.82574 9.9298 Bartlett's Test (normal distribution) Test statistic = 3.31, p-value = 0.191 Levene's Test (any continuous distribution) Test statistic = 2.95, p-value = 0.103 Test for Equal Variances: C11 versus C12 Executing from file: 252Levene3.MTB Data Display Row 1 2 3 4 C21 16.0 21.0 18.0 14.5 C22 19 20 21 20 C23 24 21 22 25 Data Display median1 median2 median3 17.0000 20.0000 23.0000 Data Display Row 1 2 3 4 C21 -1.0 4.0 1.0 -2.5 C22 -1 0 1 0 C23 1 -2 -1 2 Data Display Row 1 2 3 4 C21 1.0 4.0 1.0 2.5 C22 1 0 1 0 C23 1 2 1 2 38 251y0631s1 12/12/06 One-way ANOVA: C21, C22, C23 Source DF Factor 2 Error 9 Total 11 S = 0.9538 Level C21 C22 C23 N 4 4 4 SS MS F P 5.375 2.688 2.95 0.103 8.188 0.910 13.563 R-Sq = 39.63% R-Sq(adj) = 26.22% Mean 2.1250 0.5000 1.5000 StDev 1.4361 0.5774 0.5774 Individual 95% CIs For Mean Based on Pooled StDev ------+---------+---------+---------+--(----------*----------) (----------*----------) (----------*----------) ------+---------+---------+---------+--0.0 1.0 2.0 3.0 Pooled StDev = 0.9538 39 251y0631s1 12/12/06 Take-Home Problem 2, Version 4 MTB > WOpen "C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06032004.MTW". Retrieving worksheet from file: 'C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06032-004.MTW' Worksheet was saved on Thu Nov 30 2006 Results for: 252x06032-004.MTW MTB > exec '252oneW306032' Executing from file: 252oneW306032.MTB Executing from file: 2522onw3.MTB One-way ANOVA: 1, 2, 3 Source DF Factor 2 Error 9 Total 11 S = 1.915 Level 1 2 3 N 4 4 4 SS MS F P 60.67 30.33 8.27 0.009 33.00 3.67 93.67 R-Sq = 64.77% R-Sq(adj) = 56.94% Mean 17.500 20.000 23.000 StDev 2.646 0.816 1.826 Individual 95% CIs For Mean Based on Pooled StDev ---------+---------+---------+---------+ (--------*--------) (--------*--------) (--------*--------) ---------+---------+---------+---------+ 17.5 20.0 22.5 25.0 Pooled StDev = 1.915 Data Display Row 1 2 3 4 1 16 21 18 15 2 19 20 21 20 3 24 21 22 25 Data Display Row 1 2 3 4 x1sq 256 441 324 225 x2sq 361 400 441 400 x3sq 576 441 484 625 Data Display sumx1 sumx2 sumx3 n1 n2 n3 smx1sq smx2sq smx3sq 70.0000 80.0000 92.0000 4.00000 4.00000 4.00000 1246.00 1602.00 2126.00 Data Display x1bar x2bar x3bar 17.5000 20.0000 23.0000 40 251y0631s1 12/12/06 Data Display Row 1 2 3 4 r1 2 8 3 1 r2 4.0 5.5 8.0 5.5 r3 11 8 10 12 Kruskal-Wallis Test: C11 versus C12 Kruskal-Wallis Test on C11 C12 N Median Ave Rank Z 1 4 17.00 3.5 -2.04 2 4 20.00 5.8 -0.51 3 4 23.00 10.3 2.55 Overall 12 6.5 H = 7.27 DF = 2 P = 0.026 H = 7.40 DF = 2 P = 0.025 (adjusted for ties) * NOTE * One or more small samples Test for Equal Variances: C11 versus C12 95% Bonferroni confidence intervals for standard deviations C12 N Lower StDev Upper 1 4 1.33751 2.64575 14.3897 2 4 0.41276 0.81650 4.4408 3 4 0.92297 1.82574 9.9298 Bartlett's Test (normal distribution) Test statistic = 3.01, p-value = 0.222 Levene's Test (any continuous distribution) Test statistic = 2.63, p-value = 0.126 Test for Equal Variances: C11 versus C12 Executing from file: 252Levene3.MTB Data Display Row 1 2 3 4 C21 16 21 18 15 C22 19 20 21 20 C23 24 21 22 25 Data Display median1 median2 median3 17.0000 20.0000 23.0000 Data Display Row 1 2 3 4 C21 -1 4 1 -2 C22 -1 0 1 0 C23 1 -2 -1 2 Data Display Row 1 2 3 4 C21 1 4 1 2 C22 1 0 1 0 C23 1 2 1 2 41 251y0631s1 12/12/06 One-way ANOVA: C21, C22, C23 Source DF Factor 2 Error 9 Total 11 S = 0.9428 Level C21 C22 C23 N 4 4 4 SS MS F P 4.667 2.333 2.63 0.126 8.000 0.889 12.667 R-Sq = 36.84% R-Sq(adj) = 22.81% Mean 2.0000 0.5000 1.5000 StDev 1.4142 0.5774 0.5774 Individual 95% CIs For Mean Based on Pooled StDev ------+---------+---------+---------+--(----------*----------) (----------*----------) (----------*----------) ------+---------+---------+---------+--0.0 1.0 2.0 3.0 Pooled StDev = 0.9428 42 251y0631s1 12/12/06 Take-Home Problem 2, Version 5 MTB > WOpen "C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06032005.MTW". Retrieving worksheet from file: 'C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06032-005.MTW' Worksheet was saved on Thu Nov 30 2006 Results for: 252x06032-005.MTW MTB > exec '252oneW306032' Executing from file: 252oneW306032.MTB Executing from file: 2522onw3.MTB One-way ANOVA: 1, 2, 3 Source DF Factor 2 Error 9 Total 11 S = 1.847 Level 1 2 3 N 4 4 4 SS MS F P 58.04 29.02 8.51 0.008 30.69 3.41 88.73 R-Sq = 65.41% R-Sq(adj) = 57.73% Mean 17.625 20.000 23.000 StDev 2.496 0.816 1.826 Individual 95% CIs For Mean Based on Pooled StDev --------+---------+---------+---------+(--------*-------) (-------*-------) (-------*-------) --------+---------+---------+---------+17.5 20.0 22.5 25.0 Pooled StDev = 1.847 Data Display Row 1 2 3 4 1 16.0 21.0 18.0 15.5 2 19 20 21 20 3 24 21 22 25 Data Display Row 1 2 3 4 x1sq 256.00 441.00 324.00 240.25 x2sq 361 400 441 400 x3sq 576 441 484 625 Data Display sumx1 sumx2 sumx3 n1 n2 n3 smx1sq smx2sq smx3sq 70.5000 80.0000 92.0000 4.00000 4.00000 4.00000 1261.25 1602.00 2126.00 Data Display x1bar x2bar x3bar 17.6250 20.0000 23.0000 43 251y0631s1 12/12/06 Data Display Row 1 2 3 4 r1 2 8 3 1 r2 4.0 5.5 8.0 5.5 r3 11 8 10 12 Kruskal-Wallis Test: C11 versus C12 Kruskal-Wallis Test on C11 C12 N Median Ave Rank Z 1 4 17.00 3.5 -2.04 2 4 20.00 5.8 -0.51 3 4 23.00 10.3 2.55 Overall 12 6.5 H = 7.27 DF = 2 P = 0.026 H = 7.40 DF = 2 P = 0.025 (adjusted for ties) * NOTE * One or more small samples Test for Equal Variances: C11 versus C12 95% Bonferroni confidence intervals for standard deviations C12 N Lower StDev Upper 1 4 1.26172 2.49583 13.5743 2 4 0.41276 0.81650 4.4408 3 4 0.92297 1.82574 9.9298 Bartlett's Test (normal distribution) Test statistic = 2.75, p-value = 0.253 Levene's Test (any continuous distribution) Test statistic = 2.22, p-value = 0.164 Test for Equal Variances: C11 versus C12 Executing from file: 252Levene3.MTB Data Display Row 1 2 3 4 C21 16.0 21.0 18.0 15.5 C22 19 20 21 20 C23 24 21 22 25 Data Display median1 median2 median3 17.0000 20.0000 23.0000 Data Display Row 1 2 3 4 C21 -1.0 4.0 1.0 -1.5 C22 -1 0 1 0 C23 1 -2 -1 2 Data Display Row 1 2 3 4 C21 1.0 4.0 1.0 1.5 C22 1 0 1 0 C23 1 2 1 2 44 251y0631s1 12/12/06 One-way ANOVA: C21, C22, C23 Source DF Factor 2 Error 9 Total 11 S = 0.9538 Level C21 C22 C23 N 4 4 4 SS MS F P 4.042 2.021 2.22 0.164 8.188 0.910 12.229 R-Sq = 33.05% R-Sq(adj) = 18.17% Mean 1.8750 0.5000 1.5000 StDev 1.4361 0.5774 0.5774 Individual 95% CIs For Mean Based on Pooled StDev ------+---------+---------+---------+--(----------*----------) (----------*----------) (----------*----------) ------+---------+---------+---------+--0.0 1.0 2.0 3.0 Pooled StDev = 0.9538 45 251y0631s1 12/12/06 Take-Home Problem 2, Version 6 MTB > WOpen "C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06032006.MTW". Retrieving worksheet from file: 'C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06032-006.MTW' Worksheet was saved on Thu Nov 30 2006 Results for: 252x06032-006.MTW MTB > exec '252oneW306032' Executing from file: 252oneW306032.MTB Executing from file: 2522onw3.MTB One-way ANOVA: 1, 2, 3 Source DF Factor 2 Error 9 Total 11 S = 1.787 Level 1 2 3 N 4 4 4 SS MS F P 55.50 27.75 8.69 0.008 28.75 3.19 84.25 R-Sq = 65.88% R-Sq(adj) = 58.29% Mean 17.750 20.000 23.000 StDev 2.363 0.816 1.826 Individual 95% CIs For Mean Based on Pooled StDev -------+---------+---------+---------+-(-------*-------) (-------*-------) (-------*-------) -------+---------+---------+---------+-17.5 20.0 22.5 25.0 Pooled StDev = 1.787 Data Display Row 1 2 3 4 1 16 21 18 16 2 19 20 21 20 3 24 21 22 25 Data Display Row 1 2 3 4 x1sq 256 441 324 256 x2sq 361 400 441 400 x3sq 576 441 484 625 Data Display sumx1 sumx2 sumx3 n1 n2 n3 smx1sq smx2sq smx3sq 71.0000 80.0000 92.0000 4.00000 4.00000 4.00000 1277.00 1602.00 2126.00 Data Display x1bar x2bar x3bar 17.7500 20.0000 23.0000 46 251y0631s1 12/12/06 Data Display Row 1 2 3 4 r1 1.5 8.0 3.0 1.5 r2 4.0 5.5 8.0 5.5 r3 11 8 10 12 Kruskal-Wallis Test: C11 versus C12 Kruskal-Wallis Test on C11 C12 N Median Ave Rank Z 1 4 17.00 3.5 -2.04 2 4 20.00 5.8 -0.51 3 4 23.00 10.3 2.55 Overall 12 6.5 H = 7.27 DF = 2 P = 0.026 H = 7.43 DF = 2 P = 0.024 (adjusted for ties) * NOTE * One or more small samples Test for Equal Variances: C11 versus C12 95% Bonferroni confidence intervals for standard deviations C12 1 2 3 N 4 4 4 Lower 1.19452 0.41276 0.92297 StDev 2.36291 0.81650 1.82574 Upper 12.8514 4.4408 9.9298 Bartlett's Test (normal distribution) Test statistic = 2.52, p-value = 0.283 Levene's Test (any continuous distribution) Test statistic = 1.80, p-value = 0.220 Test for Equal Variances: C11 versus C12 Executing from file: 252Levene3.MTB Data Display Row 1 2 3 4 C21 16 21 18 16 C22 19 20 21 20 C23 24 21 22 25 Data Display median1 median2 median3 17.0000 20.0000 23.0000 Data Display Row 1 2 3 4 C21 -1 4 1 -1 C22 -1 0 1 0 C23 1 -2 -1 2 Data Display Row 1 2 3 4 C21 1 4 1 1 C22 1 0 1 0 C23 1 2 1 2 47 251y0631s1 12/12/06 One-way ANOVA: C21, C22, C23 Source Factor Error Total DF 2 9 11 S = 0.9860 SS 3.500 8.750 12.250 Level C21 C22 C23 N 4 4 4 MS 1.750 0.972 R-Sq = 28.57% Mean 1.7500 0.5000 1.5000 StDev 1.5000 0.5774 0.5774 F 1.80 P 0.220 R-Sq(adj) = 12.70% Individual 95% CIs For Mean Based on Pooled StDev ------+---------+---------+---------+--(----------*-----------) (----------*----------) (----------*----------) ------+---------+---------+---------+--0.0 1.0 2.0 3.0 Pooled StDev = 0.9860 48 251y0631s1 12/12/06 Take-Home Problem 2, Version 7 MTB > WOpen "C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06032007.MTW". Retrieving worksheet from file: 'C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06032-007.MTW' Worksheet was saved on Thu Nov 30 2006 Results for: 252x06032-007.MTW MTB > exec '252oneW306032' Executing from file: 252oneW306032.MTB Executing from file: 2522onw3.MTB One-way ANOVA: 1, 2, 3 Source DF Factor 2 Error 9 Total 11 S = 1.738 Level 1 2 3 N 4 4 4 SS MS F P 53.04 26.52 8.78 0.008 27.19 3.02 80.23 R-Sq = 66.11% R-Sq(adj) = 58.58% Mean 17.875 20.000 23.000 StDev 2.250 0.816 1.826 Individual 95% CIs For Mean Based on Pooled StDev ------+---------+---------+---------+--(-------*------) (-------*-------) (-------*-------) ------+---------+---------+---------+--17.5 20.0 22.5 25.0 Pooled StDev = 1.738 Data Display Row 1 2 3 4 1 16.0 21.0 18.0 16.5 2 19 20 21 20 3 24 21 22 25 Data Display Row 1 2 3 4 x1sq 256.00 441.00 324.00 272.25 x2sq 361 400 441 400 x3sq 576 441 484 625 Data Display sumx1 sumx2 sumx3 n1 n2 n3 smx1sq smx2sq smx3sq 71.5000 80.0000 92.0000 4.00000 4.00000 4.00000 1293.25 1602.00 2126.00 Data Display x1bar x2bar x3bar 17.8750 20.0000 23.0000 49 251y0631s1 12/12/06 Data Display Row 1 2 3 4 r1 1 8 3 2 r2 4.0 5.5 8.0 5.5 r3 11 8 10 12 Kruskal-Wallis Test: C11 versus C12 Kruskal-Wallis Test on C11 C12 N Median Ave Rank Z 1 4 17.25 3.5 -2.04 2 4 20.00 5.8 -0.51 3 4 23.00 10.3 2.55 Overall 12 6.5 H = 7.27 DF = 2 P = 0.026 H = 7.40 DF = 2 P = 0.025 (adjusted for ties) * NOTE * One or more small samples Test for Equal Variances: C11 versus C12 95% Bonferroni confidence intervals for standard deviations C12 N Lower StDev Upper 1 4 1.13744 2.25000 12.2373 2 4 0.41276 0.81650 4.4408 3 4 0.92297 1.82574 9.9298 Bartlett's Test (normal distribution) Test statistic = 2.34, p-value = 0.310 Levene's Test (any continuous distribution) Test statistic = 1.67, p-value = 0.241 Test for Equal Variances: C11 versus C12 Executing from file: 252Levene3.MTB Data Display Row 1 2 3 4 C21 16.0 21.0 18.0 16.5 C22 19 20 21 20 C23 24 21 22 25 Data Display median1 median2 median3 17.2500 20.0000 23.0000 Data Display Row 1 2 3 4 C21 -1.25 3.75 0.75 -0.75 C22 -1 0 1 0 C23 1 -2 -1 2 Data Display Row 1 2 3 4 C21 1.25 3.75 0.75 0.75 C22 1 0 1 0 C23 1 2 1 2 50 251y0631s1 12/12/06 One-way ANOVA: C21, C22, C23 Source DF Factor 2 Error 9 Total 11 S = 0.9538 Level C21 C22 C23 N 4 4 4 SS MS F P 3.042 1.521 1.67 0.241 8.188 0.910 11.229 R-Sq = 27.09% R-Sq(adj) = 10.88% Mean 1.6250 0.5000 1.5000 StDev 1.4361 0.5774 0.5774 Individual 95% CIs For Mean Based on Pooled StDev ------+---------+---------+---------+--(----------*----------) (----------*----------) (----------*----------) ------+---------+---------+---------+--0.0 1.0 2.0 3.0 Pooled StDev = 0.9538 51 251y0631s1 12/12/06 Take-Home Problem 2, Version 8 MTB > WOpen "C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06032008.MTW". Retrieving worksheet from file: 'C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06032-008.MTW' Worksheet was saved on Thu Nov 30 2006 Results for: 252x06032-008.MTW MTB > exec '252oneW306032' Executing from file: 252oneW306032.MTB Executing from file: 2522onw3.MTB One-way ANOVA: 1, 2, 3 Source DF Factor 2 Error 9 Total 11 S = 1.700 Level 1 2 3 N 4 4 4 SS MS F P 50.67 25.33 8.77 0.008 26.00 2.89 76.67 R-Sq = 66.09% R-Sq(adj) = 58.55% Mean 18.000 20.000 23.000 StDev 2.160 0.816 1.826 Individual 95% CIs For Mean Based on Pooled StDev ------+---------+---------+---------+--(-------*-------) (-------*-------) (-------*-------) ------+---------+---------+---------+--17.5 20.0 22.5 25.0 Pooled StDev = 1.700 Data Display Row 1 2 3 4 1 16 21 18 17 2 19 20 21 20 3 24 21 22 25 Data Display Row 1 2 3 4 x1sq 256 441 324 289 x2sq 361 400 441 400 x3sq 576 441 484 625 Data Display sumx1 sumx2 sumx3 n1 n2 n3 smx1sq smx2sq smx3sq 72.0000 80.0000 92.0000 4.00000 4.00000 4.00000 1310.00 1602.00 2126.00 Data Display x1bar x2bar x3bar 18.0000 20.0000 23.0000 52 251y0631s1 12/12/06 Data Display Row 1 2 3 4 r1 1 8 3 2 r2 4.0 5.5 8.0 5.5 r3 11 8 10 12 Kruskal-Wallis Test: C11 versus C12 Kruskal-Wallis Test on C11 C12 N Median Ave Rank Z 1 4 17.50 3.5 -2.04 2 4 20.00 5.8 -0.51 3 4 23.00 10.3 2.55 Overall 12 6.5 H = 7.27 DF = 2 P = 0.026 H = 7.40 DF = 2 P = 0.025 (adjusted for ties) * NOTE * One or more small samples Test for Equal Variances: C11 versus C12 95% Bonferroni confidence intervals for standard deviations C12 N Lower StDev Upper 1 4 1.09207 2.16025 11.7491 2 4 0.41276 0.81650 4.4408 3 4 0.92297 1.82574 9.9298 Bartlett's Test (normal distribution) Test statistic = 2.20, p-value = 0.332 Levene's Test (any continuous distribution) Test statistic = 1.50, p-value = 0.274 Test for Equal Variances: C11 versus C12 Executing from file: 252Levene3.MTB Data Display Row 1 2 3 4 C21 16 21 18 17 C22 19 20 21 20 C23 24 21 22 25 Data Display median1 median2 median3 17.5000 20.0000 23.0000 Data Display Row 1 2 3 4 C21 -1.5 3.5 0.5 -0.5 C22 -1 0 1 0 C23 1 -2 -1 2 Data Display Row 1 2 3 4 C21 1.5 3.5 0.5 0.5 C22 1 0 1 0 C23 1 2 1 2 53 251y0631s1 12/12/06 One-way ANOVA: C21, C22, C23 Source DF Factor 2 Error 9 Total 11 S = 0.9428 Level C21 C22 C23 N 4 4 4 SS MS F P 2.667 1.333 1.50 0.274 8.000 0.889 10.667 R-Sq = 25.00% R-Sq(adj) = 8.33% Mean 1.5000 0.5000 1.5000 StDev 1.4142 0.5774 0.5774 Individual 95% CIs For Mean Based on Pooled StDev -------+---------+---------+---------+-(-------------*------------) (------------*-------------) (-------------*------------) -------+---------+---------+---------+-0.00 0.80 1.60 2.40 Pooled StDev = 0.9428 54 251y0631s1 12/12/06 Take-Home Problem 2, Version 9 MTB > WOpen "C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06032009.MTW". Retrieving worksheet from file: 'C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06032-009.MTW' Worksheet was saved on Thu Nov 30 2006 Results for: 252x06032-009.MTW MTB > exec '252oneW306032' Executing from file: 252oneW306032.MTB Executing from file: 2522onw3.MTB One-way ANOVA: 1, 2, 3 Source DF Factor 2 Error 9 Total 11 S = 1.673 Level 1 2 3 N 4 4 4 SS MS F P 48.38 24.19 8.64 0.008 25.19 2.80 73.56 R-Sq = 65.76% R-Sq(adj) = 58.15% Mean 18.125 20.000 23.000 StDev 2.097 0.816 1.826 Individual 95% CIs For Mean Based on Pooled StDev -----+---------+---------+---------+---(-------*------) (-------*-------) (-------*-------) -----+---------+---------+---------+---17.5 20.0 22.5 25.0 Pooled StDev = 1.673 Data Display Row 1 2 3 4 1 16.0 21.0 18.0 17.5 2 19 20 21 20 3 24 21 22 25 Data Display Row 1 2 3 4 x1sq 256.00 441.00 324.00 306.25 x2sq 361 400 441 400 x3sq 576 441 484 625 Data Display sumx1 sumx2 sumx3 n1 n2 n3 smx1sq smx2sq smx3sq 72.5000 80.0000 92.0000 4.00000 4.00000 4.00000 1327.25 1602.00 2126.00 Data Display x1bar x2bar x3bar 18.1250 20.0000 23.0000 55 251y0631s1 12/12/06 Data Display Row 1 2 3 4 r1 1 8 3 2 r2 4.0 5.5 8.0 5.5 r3 11 8 10 12 Kruskal-Wallis Test: C11 versus C12 Kruskal-Wallis Test on C11 C12 N Median Ave Rank Z 1 4 17.75 3.5 -2.04 2 4 20.00 5.8 -0.51 3 4 23.00 10.3 2.55 Overall 12 6.5 H = 7.27 DF = 2 P = 0.026 H = 7.40 DF = 2 P = 0.025 (adjusted for ties) * NOTE * One or more small samples Test for Equal Variances: C11 versus C12 95% Bonferroni confidence intervals for standard deviations C12 N Lower StDev Upper 1 4 1.05991 2.09662 11.4031 2 4 0.41276 0.81650 4.4408 3 4 0.92297 1.82574 9.9298 Bartlett's Test (normal distribution) Test statistic = 2.11, p-value = 0.348 Levene's Test (any continuous distribution) Test statistic = 1.31, p-value = 0.318 Test for Equal Variances: C11 versus C12 Executing from file: 252Levene3.MTB Data Display Row 1 2 3 4 C21 16.0 21.0 18.0 17.5 C22 19 20 21 20 C23 24 21 22 25 Data Display median1 median2 median3 17.7500 20.0000 23.0000 Data Display Row 1 2 3 4 C21 -1.75 3.25 0.25 -0.25 C22 -1 0 1 0 C23 1 -2 -1 2 Data Display Row 1 2 3 4 C21 1.75 3.25 0.25 0.25 C22 1 0 1 0 C23 1 2 1 2 56 251y0631s1 12/12/06 One-way ANOVA: C21, C22, C23 Source Factor Error Total DF 2 9 11 S = 0.9538 Level C21 C22 C23 N 4 4 4 SS 2.375 8.188 10.563 MS 1.188 0.910 R-Sq = 22.49% Mean 1.3750 0.5000 1.5000 StDev 1.4361 0.5774 0.5774 F 1.31 P 0.318 R-Sq(adj) = 5.26% Individual 95% CIs For Mean Based on Pooled StDev -------+---------+---------+---------+-(------------*-------------) (------------*-------------) (-------------*------------) -------+---------+---------+---------+-0.00 0.80 1.60 2.40 Pooled StDev = 0.9538 57 251y0631s1 12/12/06 3) (Abronovic) A group of 4 workers produces defective pieces at the rates shown below during different times of the day. Personalize the data by subtracting the last digit of your student number from the 14 in the lower right corner. Use the number subtracted to label this as a version number. (Example: Good ol’ Seymour’s student number is 123456, so the 14 becomes 14 - 6 =8 and he labels it Version 6.) Time Worker’s Name Apple Plum Pear Melon Early 10 11 8 12 Morning Late 9 8 7 10 Morning Early 12 13 11 11 Afternoon Late 13 14 10 14 Afternoon Sum of Row 1 = 41, SSQ of Row 1 = 429, Sum of Column 1 = 44, SSQ of Column 1 = 494, Sum of Row 2 = 34, SSQ of Row 2 = 294, Sum of Column 2 = 46, SSQ of Column 2 = 550, Sum of Row 3 = 47, SSQ of Row 3 = 555, Sum of Column 3 = 36, SSQ of Column 3 = 334, a) Do a 2-way ANOVA on these data and explain what hypotheses you test and what the conclusions are. (6) b) Using your results from a) present two different confidence intervals for the difference between numbers of defects for the best and worst worker and for the defects from the best and second best times. Explain which of the intervals show a significant difference and why. (3) c) What other method could we use on these data to see if time of day makes a difference while allowing for cross-classification? Under what circumstances would we use it? Try it and tell what it tests and what it shows. (3) [36] a) Time Apple Plum Pear Melon Sum SS ni x i 1 2 3 4 Sum nj 10 9 12 13 44 4 11 8 13 14 46 4 x j 11 SS 494 121 x j 2 8 7 11 10 36 4 12 10 11 14 47 4 41 34 47 51 173 16 11.5 9 11.75 (10.8125) x 550 132.25 334 81 561 138.0625 1939 472.3125 2 xijk 4 4 4 4 16 n 10.25 8.50 11.75 12.75 (10.8125) x 429 294 555 661 1939 2 xijk xi 2 105.0625 72.25 138.0625 162.5625 477.9375 x i 2 x .2j . x nx 19391610.8125 19391870.5625 68.4375 SSR C x nx 4477.9375 1610.8175 1911.75 1870.5625 41.1875 SSC R x nx 4472.3125 1610.8125 1889.25 1870.5625 18.6875 SST 2 2 2 2 i. 2 2 2 .j 2 2 Source SS DF Rows 41.1875 3 Columns 18.6875 3 MS F F.05 13.7292 14.43 s 6.2292 6.55 s F 3,9 3.86 F 3,9 3.86 H0 Row means equal Column means equal Within 8.5625 9 0.95139 Total 68.4375 15 As is shown by the computed F statistics and the table values, both computed Fs exceed the table values, meaning that we will reject the null hypotheses. b) The material on confidence intervals comes from the outline for 2-way ANOVA. Note that for columns Pear is the best worker (9) and Melon the Worst (11.75), so that the difference is 2.75. For rows Time 2 is 58 251y0631s1 12/12/06 the best time (8.50) and Time 1 (10.25) is the second best, so that the difference is 1.75. 20.95139 2 MSW 0.6897 , C 4 not significant. ‘s’ stands for significant. MSW 0.95139 , 2MSW R R 1C 1 9 20.95139 0.6897 . ‘ns’ stands for 4 i. A Single Confidence Interval If we desire a single interval we use the formula for a Bonferroni Confidence Interval with m 1 . . Note that since P 1 , we must replace RC P 1 with R 1C 1 . t.9025 2.262 For row means 1 2 x1 x 2 t R1C 1 2 1.75 2.262 0.6897 1.75 1.56 . s 2MSW . So we have C For column means 1 2 x1 x2 t R1C 1 2 2.75 2.262 0.6897 2.75 1.56 . s 2MSW . So we have R ii. Scheffé Confidence Interval If we desire intervals that will simultaneously be valid for a given confidence level for all possible intervals between means, use the following formulas. Note that since P 1 , we must replace RC P 1 with R 1C 1 . 3,9 3.86 F.05 For row means, use 1 2 x1 x 2 x1 x 2 R 1FR 1,R 1C 1 R 1FR 1,R 1C 1 2MSW 2MSW So we have 1.75 33.86 0.6897 1.75 2.34 ns. C For column means, use 1 2 x1 x2 x1 x2 C 1FC 1,R 1C 1 C C 1FC 1,R 1C 1 2MSW R 2MSW 2.75 2.34 s R iii. Bonferroni Confidence Interval – not worth the effort. iv. Tukey Confidence Interval Note that since P 1 , we must replace RC P 1 with For row means, use 1 2 x1 x 2 qR ,R 1C 1 = x1 x 2 0.5qR ,R 1C 1 R 1C 1 . 4,9 q.05 4.41 MSW C 2MSW . So we have 1.75 0.70711 4.410.6897 1.75 2.15 . ns C 59 251y0631s1 12/12/06 For column means, use 1 2 x1 x2 qC ,R 1C 1 x1 x2 0.5qC ,R 1C 1 MSW R 2MSW 2.75 2.15 s R c) The alternative to 2-way ANOVA with one measurement per cell is a Friedman test. Remember that it is 10 11 8 12 9 8 7 10 , time of day was represented by rows. 12 13 11 11 13 14 10 14 10 9 12 13 11 8 13 14 If we transpose the array, columns represent time of day. . Now replace the original data 8 7 11 10 12 10 11 14 2 1 3 4 2 1 3 4 with rank within rows and sum the columns. 2 1 4 3 . As a check note that the column sums should rows that we want to compare. In the original data 3 9 1 2 4 4 12 15 445 40 and that 9 + 4 + 12 + 15 = 40. The Friedman formula reads 2 12 SRi2 3r c 1 rc c 1 i add to F2 12 92 42 12 2 15 2 345 3 466 60 69 .90 60 9.90 20 445 The Friedman table says that 9.90 has a p-value of .006. Since this is less than 5% or 1% we reject the null hypothesis that the median number of defects is the same regardless of time of day. ————— 12/1/2006 1:28:47 AM ———————————————————— Welcome to Minitab, press F1 for help. 60 251y0631s1 12/12/06 Take-Home Problem 3, Version 0 Results for: 252x06033-000.MTW MTB > exec '2522W06133' Executing from file: 2522W06133.MTB Data Display Row 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 C40 10 9 12 13 11 8 13 14 8 7 11 10 12 10 11 14 C41 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 C42 1 1 1 1 2 2 2 2 3 3 3 3 4 4 4 4 Tabulated statistics: C41, C42 Rows: C41 Columns: C42 1 2 3 4 All 1 1 1 1 2 1 1 1 3 1 1 1 4 1 1 1 All 4 4 4 Cell Contents: 1 1 1 1 4 4 4 4 4 16 Count Tabulated statistics: C41, C42 Rows: C41 Columns: C42 1 2 3 4 1 10 11 8 12 2 9 8 7 10 3 12 13 11 11 4 13 14 10 14 Cell Contents: C40 : DATA Tabulated statistics: C41, C42 Rows: C41 Columns: 1 2 1 10.00 11.00 2 9.00 8.00 3 12.00 13.00 4 13.00 14.00 All 11.00 11.50 Cell Contents: C40 C42 3 4 8.00 12.00 7.00 10.00 11.00 11.00 10.00 14.00 9.00 11.75 : Mean All 10.25 8.50 11.75 12.75 10.81 61 251y0631s1 12/12/06 Two-way ANOVA: C40 versus C41, C42 Source DF C41 3 C42 3 Error 9 Total 15 S = 0.9754 SS MS F P 41.1875 13.7292 14.43 0.001 18.6875 6.2292 6.55 0.012 8.5625 0.9514 68.4375 R-Sq = 87.49% R-Sq(adj) = 79.15% Results for: 252x06033-000.MTW MTB > WOpen "C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06033000.MTW". Retrieving worksheet from file: 'C:\Documents and Settings\RBOVE\My Documents\Minitab\252x06033-000.MTW' Worksheet was saved on Thu Nov 30 2006 MTB > Execute "C:\Documents and Settings\RBOVE\My Documents\Minitab\2522W06033.mtb" 1. Executing from file: C:\Documents and Settings\RBOVE\My Documents\Minitab\2522W06033.mtb Executing from file: 252onw4.MTB One-way ANOVA: C1, C2, C3, C4 Source DF Factor 3 Error 12 Total 15 S = 2.036 Level C1 C2 C3 C4 SS MS F P 18.69 6.23 1.50 0.264 49.75 4.15 68.44 R-Sq = 27.31% R-Sq(adj) = 9.13% Individual 95% CIs For Mean Based on Pooled StDev Mean StDev ------+---------+---------+---------+--11.000 1.826 (----------*----------) 11.500 2.646 (----------*-----------) 9.000 1.826 (----------*----------) 11.750 1.708 (----------*----------) ------+---------+---------+---------+--8.0 10.0 12.0 14.0 N 4 4 4 4 Pooled StDev = 2.036 Executing from file: 252onme4.MTB Executing from file: 252osme4.MTB Data Display Row 1 2 3 4 C1 10 9 12 13 C2 11 8 13 14 C3 8 7 11 10 C4 12 10 11 14 Data Display Row 1 2 3 4 x1sq 100 81 144 169 x2sq 121 64 169 196 x3sq 64 49 121 100 x4sq 144 100 121 196 62 251y0631s1 12/12/06 Data Display sumx1 sumx2 sumx3 sumx4 n1 n2 n3 n4 smx1sq smx2sq smx3sq smx4sq 44.0000 46.0000 36.0000 47.0000 4.00000 4.00000 4.00000 4.00000 494.000 550.000 334.000 561.000 Executing from file: 252omea4.MTB Data Display x1bar x2bar x3bar x4bar 11.0000 11.5000 9.00000 11.7500 Data Display Row 1 2 3 4 C1 10 9 12 13 C2 11 8 13 14 C3 8 7 11 10 C4 12 10 11 14 Data Display Row 1 2 3 4 C50_1 10 11 8 12 C50_2 9 8 7 10 C50_3 12 13 11 11 C50_4 13 14 10 14 C57_3 3 3 4 2 C57_4 4 4 3 4 Data Display Row 1 2 3 4 C57_1 2 2 2 3 C57_2 1 1 1 1 Friedman Test: C50 versus C51 blocked by C52 S = 9.90 DF = 3 P = 0.019 Sum of C51 N Est Median Ranks 1 4 10.656 9.0 2 4 9.156 4.0 3 4 12.531 12.0 4 4 13.281 15.0 Grand median = 11.406 63