A marine biologist is investigating the relationship between water depth and the concentration of a particular micro-organism. Data were collected from 8 different sites, as shown in the table below.
| Site | A | B | C | D | E | F | G | H |
|---|---|---|---|---|---|---|---|---|
| Depth (h h\,h m) | 120 | 50 | 250 | 180 | 300 | 100 | 220 | 80 |
| Concentration (C C\,C units/ml) | 3.8 | 2.9 | 6.4 | 7.5 | 9.8 | 4.2 | 6.1 | 2.5 |
Calculate Spearman's rank correlation coefficient for these data.
Stating your hypotheses clearly, test at the 5% level of significance whether there is evidence of a positive correlation between water depth and micro-organism concentration.
244 exam-style questions on AQA A Level Maths 2.2 L: Data presentation and interpretation, covering 2.2.1 Single-variable data diagrams, 2.2.2 Scatter diagrams and correlation, 2.2.3 Central tendency, variation and standard deviation, 2.2.4 Outliers and cleaning data, and 2.2 L: Data presentation and interpretation. Each one has a worked solution and a mark scheme showing where the marks go.