Work through the list without notes. If you cannot do a statement, follow its link, then come back. Guide = study guide; Practice = practice questions.
Understanding
- I can explain that r measures the direction and strength of a linear association only. (Guide: “One number for a linear association”; Practice Q3)
- I can state that r always lies between −1 and 1, and explain what r = 1, r = −1 and r = 0 mean. (Guide: “Properties of r”; Practice Q3)
- I can explain why r has no units and why changing units or swapping the variables does not change it. (Guide: Worked example 1; Practice Q2, Q4(b))
- I can explain why strength depends on how close r is to −1 or 1, not on its sign or on the slope. (Guide: “Properties of r”; Practice Q1, Q7)
Skills
- I can find r with technology and interpret it in context, naming strength, direction, “linear” and both variables. (Guide: Worked example 1; Practice Q4(a))
- I can compare the strengths of linear associations from their r values. (Practice Q1)
- I can show with data that a pattern is curved even when r is close to −1 or 1. (Guide: Worked example 2; Practice Q5)
- I can show how one unusual point can change r a lot. (Guide: “When r misleads (2)”; Practice Q4(c))
Reasoning
- I can explain why a value of r near −1 or 1 does not on its own justify a linear model. (Guide: Worked example 2; Practice Q5)
- I can explain why correlation does not imply causation, naming a plausible lurking variable linked to both variables. (Guide: Worked example 3; Practice Q6)
- I can describe a randomised experiment that could test a causal claim. (Practice Q6(c))
- I can spot and correct errors in statements about r. (Practice Q7)
All ticked? Move on to Topic 5.3: Linear Regression Models, or return to the course roadmap.