Researchers hypothesized that young adults would report a re

Researchers hypothesized that young adults would report a reduction in consumption of doughnuts after attending a psycho-educational intervention during which there is a discussion of a suspected link between the use of sugar, stress, and depression. Researchers selected a sample of 30 students and measured the number of doughnuts they ate in the week before the class and the number of doughnuts the same group ate in the week after the class.

Which of the following would be the appropriate numerator (estimate of treatment effect) for the formula best suited to analyze these data?

a.(mean of group 1) - (mean of group 2)

b. mean of participant difference scores  

c.correlation coefficient

d.(sample mean) - (population mean)

Solution

As this is the same sample (before and after), this is a paired t test.

Thus, we use OPTION B: mean of participant difference scores. [ANSWER]