Eighteen obese volunteers weighed themselves before and after a two-day fast.The appropriate design for testing the significance of the difference between the means is
A)related-samples t-test.
B)independent-samples t-test.
C)one-sample t-test.
D)z-test.

Question

Quizplus · Accepted Answer

A related-samples t-test, also known as a paired t-test or dependent t-test, is appropriate when comparing the means of two related (or paired) samples, such as pre- and post-test measurements. In this case, the 18 obese volunteers each have two measurements, their weight before and after the fast, which are related and paired. An independent-samples t-test would be appropriate for comparing the means of two independent groups, which is not the case here. A one-sample t-test would be appropriate if we were comparing the mean weight change to a known value, such as zero (no weight change). A z-test is used when the sample size is large and/or the population standard deviation is known, which is not the case here.

Eighteen Obese Volunteers Weighed Themselves Before and After a Two-Day