An environmental biologist conducted a study into the relationship between the distance from a highway and the lead concentration in the topsoil. She collected samples from 10 distinct locations, measuring the distance of each location from the highway (in kmkmkm) and the lead concentration (in μg/g\mu\text{g/g}μg/g).
The raw data and the sequential ranks for both variables are shown in the table below.
| Location | Distance from highway (kmkmkm) | Lead concentration (μg/g\mu\text{g/g}μg/g) | Rank of Distance | Rank of Lead concentration |
|---|---|---|---|---|
| A | 0.5 | 2.1 | 1 | 4 |
| B | 1.2 | 3.5 | 3 | 7.5 |
| C | 0.8 | 1.2 | 2 | 1 |
| D | 4.5 | 5.0 | 9 | 10 |
| E | 2.1 | 3.0 | 5 | 6 |
| F | 1.5 | 1.5 | 4 | 2 |
| G | 3.2 | 3.5 | 7 | 7.5 |
| H | 2.8 | 2.4 | 6 | 5 |
| I | 5.0 | 4.2 | 10 | 9 |
| J | 3.6 | 1.8 | 8 | 3 |
Explain why the data for lead concentration for locations B and G have both been given the rank of 7.5.
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.