Calculate a 90 percent confidence interval

Assignment Help Applied Statistics

Reference no: EM13503070

Waist-to-hip ratio was measured on 8 men just before they entered a weight loss program (time 1) and again 6 months after the program (time 2). The results are below.

Subject 1 2 3 4 5 6 7 8

Time 1 1.03 0.99 1.18 0.82 1.02 1.05 1.06 0.82

Time 2 1.00 1.02 1.12 0.78 1.06 1.00 1.08 0.76

data one;

input WHR1 WHR2;

diff = WHR1 - WHR2;

Datalines;

1.03 1.00

0.99 1.02

1.18 1.12

0.82 0.78

1.02 1.06

1.05 1.00

1.06 1.08

0.82 0.76

;

run;

a. Calculate the difference for each subject (as time 1 value minus time 2 value), then calculate the mean and standard deviation of these differences. You can do this however you like.

b. Using the information from part (a), "by hand", calculate a 90% confidence interval for the difference of the means for the two time periods (i.e., for the mean difference).

c. We want to use a paired t-test, at a = .05, to test if the mean waist-to-hip ratio is smaller at time 2 than at time 1 (i.e., test if the program is effective). Use PROC TTEST to obtain the test statistic and p-value. Turn in the printout.

d. A colleague looks at the printout and decides that we have proven that the program is not effective. Do you agree with his conclusion? Why or why not?

Reference no: EM13503070

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