A researcher was interested in the relationship between the number of hours a student used active retrieval practice (using flashcards) and their performance on a subsequent sociology exam.
As part of her research, she conducted a pilot study. A unit of a sociology course was structured into 10 equal one-hour study sessions. Eleven students, who were matched for having a similar high level of prior achievement in sociology, took part in the study.
All 11 students completed all 10 hours of study. Each student was randomly allocated a letter from A to K, which determined how many hours they spent on active retrieval practice versus passive reading of the textbook. The combinations are shown in Table 1 below.
Table 1: The number of hours each student (labelled A – K) spent on active retrieval practice and passive reading
| A | B | C | D | E | F | G | H | I | J | K | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Retrieval practice (hours) | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| Passive reading (hours) | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
Suggest one other variable for which the researcher should have matched the students. Explain how this might have affected the exam performance scores if it was not controlled.
689 exam-style questions on AQA A Level Psychology Scientific processes. Each one has a worked solution and a mark scheme showing where the marks go.