An agricultural researcher investigated whether there was a correlation between the average weekly hours of direct sunlight a crop received and its final harvest yield (in kg).
The researcher randomly selected 13 experimental crop plots. For each plot, the weekly sunlight hours were logged and the final yield was measured.
The researcher proposed a directional (one-tailed) hypothesis predicting a positive correlation between sunlight hours and harvest yield. The calculated Spearman's rho correlation coefficient was rs=0.492r_s = 0.492rs=0.492.
Table 1: Critical values of Spearman's rank correlation coefficient (rho)
| Level of significance for a one-tailed test | 0.05 | 0.025 |
| Level of significance for a two-tailed test | 0.10 | 0.05 |
|---|---|---|
| N = 12 | 0.497 | 0.581 |
| N = 13 | 0.475 | 0.553 |
| N = 14 | 0.457 | 0.534 |
| N = 15 | 0.441 | 0.514 |
| N = 16 | 0.425 | 0.497 |
Note: The calculated value of rho must be greater than or equal to the critical value for the relationship to be marked as statistically significant.
Using the information above, explain whether the researcher's hypothesis should be accepted at the 5% level of significance.
121 exam-style questions on AQA A Level Psychology Inferential testing (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.