You believe that eating an apple a day is healthy and want t

You believe that eating an apple a day is healthy and want to design an
experiment to find out. You have available 40 volunteers (22 men and 18
women) from a four-year college, all between the ages of 18 and 22. Design an
experiment to help you determine if this practice is healthy or not, and explain,
in terms of the important principles of experimental design, why you chose the
design you did.

Solution

Divide the group equally so that you have 11 men and 9 women in each group. One of the groups will be the control group, and will not eat apples. One of the groups will be the experimental group and will eat an apple a day.

Because it is impossible to double-blind the study, you should probably ask people whether they like apples or not, and put people who like apples into the apple-eating group. You will be less likely to have people drop out of the experiment if they are not avoiding a food they love or forced to eat something they hate.

However, you should try to prevent people from influencing the study by telling them it is for some other purpose, for example, does eating apples affect a student\'s GPA. Collect grade information, but also collect information about illness. After all, being too sick to attend class will affect the GPA, won\'t it?

By the way, the idea that, \"An apple a day keeps the doctor away,\" dates from a time when people got much less fresh fruit and vegetables. Most vegetables were canned or cooked to mush. As a result, many people were constipated and sought a doctor\'s help for this. Eating apples, especially eating the peel, which is full of fiber, does indeed reduce constipation. There was also a WW1 or WW2 campaign to get people to eat the apple peel, as people were more likely to eat apples in pie or make alcoholic cider out of them. (Hard cider is the REAL reason Johnny Appleseed planted apples everywhere.)