A researcher investigated whether using a new interactive online learning platform, CalculusPlus, increases the weekly independent study time of Year 13 Mathematics students. To recruit participants, the researcher posted an advertisement on an online discussion forum dedicated exclusively to students preparing for advanced mathematics university entrance exams. A volunteer sample of 12 students was obtained.
During Week 1, the participants recorded the total hours they spent studying mathematics independently (excluding lessons). During Week 2, they were given access to CalculusPlus and recorded their independent study hours again.
The data collected is shown in the table below:
| Student | Week 1: Independent study hours (without CalculusPlus) | Week 2: Independent study hours (with CalculusPlus) |
|---|---|---|
| A | 12.5 | 15.0 |
| B | 18.0 | 20.5 |
| C | 8.0 | 7.5 |
| D | 15.0 | 18.0 |
| E | 22.0 | 24.5 |
| F | 10.5 | 12.0 |
| G | 14.0 | 14.0 |
| H | 25.0 | 28.5 |
| I | 6.0 | 9.0 |
| J | 17.5 | 16.0 |
| K | 11.0 | 13.5 |
| L | 19.5 | 22.0 |
Outline one way that the sampling technique used to obtain participants for this study could have affected the generalisability of the results.
