A student extracts the following entries from the OCR large data set for the proportion of employed people travelling to work by train.
| Local Authority | Train count | Employed total | Recorded proportion |
|---|---|---|---|
| P | 1865 | 227894 | 0.00818 |
| Q | 828 | 49014 | 1.69 |
| R | missing | 91877 | 0.00767 |
| S | 469 | 37767 | 0.0124 |
Identify and explain the error in the recorded proportion for Q.
State how the entry for R should be handled before analysis.
Explain why comparing the train counts alone could give a misleading ranking of the Local Authorities.
36 exam-style questions on OCR A Level Maths 2.1 Statistical Sampling, covering 2.1.1 Population and sample, 2.1.2 Informal inferences from samples, 2.1.3 Sampling techniques, 2.1.4 Selecting or critiquing sampling techniques, and 2.1 Statistical Sampling. Each one has a worked solution and a mark scheme showing where the marks go.