Question

A data collection method is described to investigate a difference in means. In each case, determine which data analysis method is more appropriate: paired data difference in means or difference in means with two separate groups. A study investigating the effect of exercise on brain activity recruits sets of identical twins in middle age, in which one twin is randomly assigned to engage in regular exercise and the other doesn't exercise.

Short answer

The appropriate data analysis method for this study would be the paired data difference in means method.

Step-by-step solution

Analyze the Nature of Data

In the given study, sets of identical twins are used, with one twin randomly assigned to regular exercise and the other to no exercise. Notice that the twins here are not separate groups, instead each pair has an intrinsic connection or 'pairing', particularly because they are identical twins and they are being measured for the same parameter (brain activity).

Identify the Appropriate Method

Since pairs of twins were used in the study in order to facilitate the control of other variables besides regular exercise, it is more appropriate to treat the data set as paired data rather than two separate groups. Based on this consideration, the statistical method better suited for this analysis would be 'paired data difference in means' method.