For 20 districts, a researcher obtains r=−0.955r=-0.955r=−0.955 between an air-quality score x x\,x and respiratory-disease rate yyy. A given regression line for life expectancy z z\,z on x x\,x is z=76.8+0.703xz=76.8+0.703xz=76.8+0.703x.
Interpret rrr.
Estimate z z\,z when x=10.5x=10.5x=10.5.
Interpret the gradient of the regression line.
Explain why neither result alone proves that changing the air-quality score will change health outcomes.
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.