Forty-one employees of a biotechnology company participated in a study that examines the immunological and psychological effects of meditation. Twenty-five of the participants, chosen at random, completed an eight-week meditation program while the other 16 employees did no meditation. Brain wave activity across the front of the left hemisphere was measured for all participants before, immediately following, and four months after the program. (Studies have suggested that increased activity in this part of the brain is associated with decreases in negative emotions and increases in positive emotions.) All 41 people received an influenza vaccination at the end of the program and their immune response to the vaccine was measured through blood samples taken one month and two months later. All participants also completed surveys designed to measure negative and positive emotions before and after the course. The surveys produced two numerical scores (one for positive emotions and one for negative emotions) in both situations.

Meditators showed an increase in brain wave activity, a decrease in reported negative feelings, and no change in reported positive feelings. Nonmeditators showed no significant change in any of these areas. Meditators had a stronger antibody response to the vaccine than the non-meditators.

(a) What are the cases in this study? How many cases are there?

(b) What are the variables? Which are categorical and which are quantitative?

(c) Which variable is the explanatory variable?

(d) How many rows and how many columns will the dataset contain if we assume that each data case is a row and each variable is a column?