12.6 Number of Orders and Shipping Cost ($)
(a) Make a scatter plot of the data. What does it suggest about the correlation between X and Y?
7000
6000
5000
4000
3000
2000
1000
0
0
500
1000
1500
Suggests a positive correlation between x and y
(b) Use Excel, MegaStat, or MINITAB to calculate the correlation coefficient.
0.82
(c) Use Excel or Appendix D to find t.05 for a two-tailed test.
t(0.025,10)=2.228
(d) Calculate the t test statistic.
t=(0.8210)/ (1-0.822)=4.53
(e) Calculate the critical value of ra.
Critical values: -2.228 and 2.228
(f) Can you reject ? = 0?
Yes, 4.53>2.228
Orders X.........1068, 1026, 767, 885, 1156, 1146, 892, 938, 769, 677, 1174, 1009 Ship Cost
Y.......4489, 5611, 3290, 4113, 4883, 5425, 4414, 5506, 3346, 3673, 6542, 5088