An environmental psychologist investigated whether displaying a 'turn off the lights' prompt on classroom smartboards would reduce the frequency of lights being left on at the end of the day. They monitored classrooms across two wings of a university department: one wing where classrooms had the prompt displayed on screens, and another wing without any prompt. They recorded whether the lights were left on or turned off at 6:00 PM over a two-week period, categorising the rooms by department type (Humanities vs. STEM).
The table below shows the distribution of outcomes:
| Humanities Classrooms | STEM Classrooms | |
|---|---|---|
| Lights left ON | 14 | 22 |
| Lights turned OFF | 28 | 16 |
The psychologist analysed the data using a Chi-square test and obtained a calculated value of χ2=3.15\chi^2 = 3.15χ2=3.15.
Below is an extract from the table of critical values for the Chi-square test:
| Degrees of Freedom (dfdfdf) | p=0.10p = 0.10p=0.10 | p=0.05p = 0.05p=0.05 | p=0.01p = 0.01p=0.01 |
|---|---|---|---|
| 1 | 2.71 | 3.84 | 6.63 |
| 2 | 4.61 | 5.99 | 9.21 |
Write a significance statement presenting this finding, showing whether the results are significant or not at the 5% level of probability (p≤0.05p \le 0.05p≤0.05).
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.