Question

Consider a study that compares the Atkins diet to a conventional diet. A study at the University of Pennsylvania selected a sample of 63 subjects from the local population of obese adults. Researchers randomly assigned 33 to the Atkins diet and 30 subjects to a conventional diet. Test whether there is a significant difference in the mean weight loss (measured in pounds) across the two different diet programs.

Atkins	Conventional
27	26
31	26
34	29
31	24
28	25
32	22
33	27
27	24
34	25
25	28
31	30
26	27
28	25
30	23
26	20
26	22
31	29
34	28
27	21
28	25
33	22
26	24
26	22
30	25
26	29
34	24
25	26
32	21
29	22
33	21
27
29
25
Atkins	Conventional
27	26
31	26
34	29
31	24
28	25
32	22
33	27
27	24
34	25
25	28
31	30
26	27
28	25
30	23
26	20
26	22
31	29
34	28
27	21
28	25
33	22
26	24
26	22
30	25
26	29
34	24
25	26
32	21
29	22
33	21
27
29
25

I previously asked this question and when I put the data in excel, the numbers did not come out like the example. Please help. Thanks

Using software:

1. Generate summary statistics (central tendency and variability measures) for the two samples and briefly summarize what they say.
   

b.         Conduct a test of significance for the difference between the mean weight across the different diet programs. Be sure to show the output from the software and interpret the results.

c. Construct a 95% confidence interval for the difference parameter in mean weight lost and make an interpretation.

d. Finally, are there any other factors, besides the type of diet, that could possibly influence weight loss (identify at least 2)? Include a brief explanation of each.

Answer 1

We use minitab to solve this question-

a) Summary Statistics
Variable Mean SE Mean StDev Minimum Q1 Median Q3 Maximum Range
Atkins 29.212 0.536 3.080 25.000 26.000 29.000 32.000 34.000 9.000
Conventional 24.733 0.510 2.791 20.000 22.000 25.000 27.000 30.000 10.000

b)
P-value = 0.000 < alpha therefore there is significant fifference between the mean weight across the different diet programme.
c) 95% Confidence Interval is ,
(2.999, 5.958)
There is 95 % chance that mean difference between Atkins diet and Conventional diet lies in the interval (2.999, 5.958).
d) There are no any other factors, besides the type of diet, that could possibly influence weight loss.