Using Excell *Bring Money for Yearbook! Computer Software There are two statistical software packages that are often used Minitab JMP Once you understand the statistical ideas, you can read and work with almost any software output. DATA Analysis (school computers) Go to File Down to “Options” Click on “Add ins” Mark the first 2 – Data Pak Click on “Go” It will now be found under Data in the Data Analysis section. DATA Analysis (Windows 97) Go to Tools Click on “Add ins” Check 1st 2 It will now be found under Tools DATA Analysis (Vista) Go to Tools Click on “Add ins” Check 1st 2 It will now be found under Tools A study of nutrition in developing countries collected data from the Egyptian village of Nahya. Here are the mean weights (in kg) for 170 infants in Nahya who were weighed each month during their first year of life: Age (mths) Weight (kg) 1 4.3 Put independent variable in column A. 2 5.1 Put dependent variable in column B. 3 5.7 Go to Data Analysis – to Regression 4 6.3 5 6.8 6 7.1 Hightlight A column for x-range 7 7.2 Click on labels (if you included them) 8 7.2 Click on output – click space to put it 9 7.2 10 7.2 11 7.5 12 7.8 Hightlight B column for y-range. If you want the normal probability plot, click on it. Try it: Computer Printout Example.xlsx What you get! SUMMARY OUTPUT Regression Statistics Multiple R 0.906552235 = r R Square 0.821836955 Adjusted R Square Standard Error Observations 0.80402065 0.470339361 12 = n Ignore this part of the print out for now…you’ll get it later in the spring! ANOVA df SS MS F 1 10.20448 10.20448 46.12836 Residual 10 2.212191 0.221219 Total 11 12.41667 Regression Significance F 4.79E-05 The y – intercept (a) Standard Error t Stat 4.88030303 0.289474 0.267132867 0.039332 Coefficients Intercept Age (mths) P-value Lower 95% Upper 95% 16.85922 1.13E-08 4.235315 5.525291 6.791786 4.79E-05 0.179496 0.354769 The slope (b) The x-variable Scatter plot with regression line: (for school computers) Highlight all of the data, including labels Click on Insert Click on Scatter Click on top left graph To get the regression line you right click on one of the points and choose trendline and click enter. Scatter plot with regression line: (for windows 97) Click on Chart wizard Scatter(xy) 1st one click Next Highlight Data Range (do not include labels) & press next Type in labels for x & y Press Next & Finish To get line – click on point & press add trendline Normal Probability Plots Used to determine if the data is approximately normal If it appears to be a straight line – then it’s approximately normal Weight (kg) Normal Probability Plot 10 5 0 0 20 40 60 80 Sample Percentile 100 120 Find equation for the data below comparing the intensity of a baby’s cry & their IQ. ANOVA df SS MS F Regression 1 2895.524 2895.524 20.28253 Residual 8 1142.076 142.7595 Total 9 Coefficient s Intercept 74.26985 Crying 2.604357 Significance F 0.001993 4037.6 Standard Error t Stat 10.0478 7.391653 P-value Lower 95% Upper 95% 7.68E-05 51.09958 97.44012 0.578282 4.503613 0.001993 1.270837 3.937877 Residual Plot Looking for no – pattern in order for it to be a good linear model Click on residual plot when doing the regression to see it. Homework Worksheet