A researcher records the engine capacity and the CO2 _2\,2 emission of 90 cars, all of the same make, and finds a correlation coefficient of 0.78. She concludes that cars with larger engines pollute more.
State two things the value 0.78 does not tell the researcher.
Explain how the fact that all 90 cars are of the same make limits her conclusion.
Describe a study that would allow higher CO2 _2\,2 emissions to be attributed to engine capacity itself.
157 exam-style questions on AQA A Level Maths 2.2.2 Scatter diagrams and correlation. Each one has a worked solution and a mark scheme showing where the marks go.