Reducing food waste in schools is key to sustainability. An environmental researcher investigated the impact of introducing a "trayless dining" policy in a school cafeteria on the amount of food waste produced by student groups.
She conducted an experiment using a sample of 12 class groups obtained via opportunity sampling. In the first week, class groups dined with trays as normal and the mass of food waste they left behind during lunch was recorded in kilograms (kg). In the second week, trayless dining was implemented and the mass of food waste for the same class groups was recorded. The data collected is shown in the table below:
| Class Group | Mass of food waste during lunch service (kg) | |
|---|---|---|
| With trays | Trayless dining | |
| a | 12.4 | 10.1 |
| b | 18.5 | 15.2 |
| c | 22.1 | 18.3 |
| d | 15.8 | 14.1 |
| e | 9.2 | 9.5 |
| f | 25.3 | 20.2 |
| g | 14.7 | 11.2 |
| h | 11.0 | 11.0 |
| i | 19.4 | 17.5 |
| j | 16.3 | 13.0 |
| k | 20.8 | 19.1 |
| l | 13.5 | 13.2 |
Outline one strength of using the standard deviation rather than the variance as the measure of dispersion for the data collected in this study.
513 exam-style questions on OCR A Level Psychology Data recording, analysis and presentation. Each one has a worked solution and a mark scheme showing where the marks go.