SUGGESTED ANSWER TO QUESTION 2A-1

We need to test the 2-for-1 Rule against other possible rules-of-thumb, such as the 1-for-1 Rule and the 3-for-1 Rule. This would require a modification of the study described in the lesson:

 
Group 1
Group 2
Group 3
Monday
studies 1 hour
studies 2 hours
studies 3 hours
Tuesday
studies 1 hour
studies 2 hours
studies 3 hours
Wednesday
studies 1 hour
studies 2 hours
studies 3 hours
Thursday
studies 1 hour
studies 2 hours
studies 3 hours
Friday
Test
Test
Test

In this study, Group 1 is using a 1-for-1 Rule, Group 2 is using a 2-for-2 Rule, and Group 3 is using a 3-for-3 Rule. As you can see, the extraneous variable of retention interval is being controlled for. And we could control for the extraneous variable of fatigue by making sure that everyone rests for, say, 30 minutes after each hour of studying. If you thought of other extraneous variables, your study should include controls for them.

If we found that Group 2 did better on the test than did Group 1, and that there was little or no increase in test scores in Group 3 compared to Group 2 (that is, if studying three hours per day did not improve test scores appreciably over the scores obtained by studying two hours per day), then we could conclude that the 2-for-1 Rule was the best of the three.

Of course, it is possible that Group 3 will do much better than Groups 1 and 2. In this case, the study will have shown that you should study at least three hours outside of class for every hour spent in class if you want to have the best chance of getting a good grade. Or we may find that there are no appreciable differences among the three groups, which would suggest that you need to study only about one hour (or less) outside of class for every hour spent in class.

Of course, we then might want to expand the study in order to look at different kinds of courses. Perhaps natural-science courses require a different rule-of-thumb than behavioral-science courses; and perhaps behavioral-science courses require a different rule-of-thumb than humanities courses (and so on).

In other words, in a scientific study, we attempt to evaluate different answers to a question in order to see if the evidence points to a best answer to the question. A scientific study is simply critical thinking performed in a formalized manner.