A scatter diagram of height against mass for 30 animals contains two distinct clusters. The animals in one cluster are juveniles and those in the other are adults. A single regression line fitted to all 30 points has strong positive correlation.
Explain why fitting one regression line to all 30 animals may be misleading.
Suggest a more appropriate analysis.
Explain why the strong correlation does not establish that increasing an animal's mass causes it to grow taller.
278 exam-style questions on CCEA A Level Maths 2.5 Data presentation and interpretation, covering 2.5.1 Data presentation and interpretation, 2.5.2 Data presentation and interpretation, 2.5.3 Data presentation and interpretation, 2.5.4 Data presentation and interpretation, 2.5.5 Data presentation and interpretation, 2.5.6 Data presentation and interpretation, 2.5.7 Data presentation and interpretation, 2.5.8 Data presentation and interpretation, 2.5.9 Data presentation and interpretation, and 2.5 Data presentation and interpretation. Each one has a worked solution and a mark scheme showing where the marks go.