A report on 120 cars from the AQA Large Data Set states the following.
"The correlation coefficient between CO2 _2\,2 emission and CO emission is 0.81. Cutting CO2 _2\,2 emissions across England by 1 g/km per car would therefore cut CO emissions by 0.0025 g/km per car."
State what is wrong with the step from the correlation coefficient to the conclusion about cutting emissions.
The CO2 _2\,2 emissions in the data range from 100 g/km to 245 g/km. Explain why the figure 0.0025 g/km should not be applied to a car outside this range.
Using your knowledge of the Large Data Set, give two reasons why the conclusion about England is not supported.
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.