Studying health risk and perceptions of riskEdexcel A-Level Biology A: Mind map

Exam questions on Studying health risk and perceptions of risk

1. In a study of 5 000 adults aged 50 to 70, researchers recorded whether each person owned a dog and followed all of them for 10 years. The number of deaths from coronary heart disease (CHD) per 1 000 people per year was 2.1 for dog owners and 3.4 for people who did not own a dog.
   Explain why the researchers cannot conclude that owning a dog reduces the risk of CHD.2 marks
2. Two towns recorded their deaths from CHD in the same year. Town X has a population of 32 000 and recorded 48 deaths from CHD. Town Y has a population of 12 500 and recorded 30 deaths from CHD.
   Calculate how many times greater the CHD mortality rate is in Town Y than in Town X, and suggest one factor, other than the town itself, that could explain the difference.2 marks
3. A researcher wants to find out whether eating a high-salt diet raises blood pressure. She asks for volunteers at a local running club and recruits 20 of them. Ten eat a high-salt diet for four weeks and ten eat their normal diet. She measures each person's blood pressure once, at the end of the four weeks.
   Evaluate the way the researcher selected her sample and the size of her sample.3 marks