An educational psychologist investigated the 'spacing effect' to see if the distribution of study sessions affects vocabulary retention. Two independent groups of students were used. Group A studied 30 foreign vocabulary words using spaced retrieval practice over a week, while Group B studied the same words in a single massed cramming session. Both groups completed a retention test one week later.
Table 2: Mean vocabulary retention test scores out of 25 for the two groups
| Spaced Retrieval Group | Massed Cramming Group | |
|---|---|---|
| Mean score out of 25 | 19.2 | 13.5 |
Explain which statistical test the researchers could have used to analyse the data in Table 2.
638 exam-style questions on Edexcel A Level Psychology Methods. Each one has a worked solution and a mark scheme showing where the marks go.