Twenty First Century Science

Dear Dr Mariella
Key Assessment Task Marking criteria H

1 A link between two things. If the outcome gets steadily bigger, or smaller, when the factor gets bigger we say that there is a correlation between the two.

2 There are many possible answers. Check with your teacher if you are unsure whether your answer describes a correlation.

3 The bigger waist-to-hip ratio and the bigger risk of heart disease could both be caused something else.

4 The Dallas Heart Study shows a correlation between a man’s and a woman’s waist-to-hip ratio and the likelihood that they will have fat in the arteries.

5 For group 1, the ‘likelihood of fat in the arteries compared with group 1’ is 1.0. The group is compared with itself so they are both the same. When two things are exactly the same, dividing one by the other = 1.0

6
a Group 1. (Kerry says she has a waist-to-hip ratio of 0.75)
b It means her risk of developing heart disease is lower, but there are many factors that contribute to her risk of heart disease, so she cannot be sure.

7
a Group 4. (Kerry says he has a waist-to-hip ratio of 0.98)
b 3.0 times (A person in group 4 is 3.0 times more likely to suffer from heart disease than a person in group 1 - and Kerry is in group 1)

8 Fat deposits can build-up inside arteries. This can block the arteries, raising blood pressure and making it harder for the heart to pump blood around the body.

9 Kerry’s husband has a waist-to-hip ratio of 0.98, so he has a greater risk of heart disease than a man with a waist-to-hip ratio of 0.9 or less. However, this does not mean that Kerry’s husband will definitely suffer from heart disease. Other factors contribute to a person’s risk of heart disease.

10 Men with big waist-to-hip ratios have an increased risk of heart disease. Each of these men is at increased risk. Just because his Dad has not developed heart disease, does not mean that Kerry’s husband will not suffer from heart disease.

11 The data do not explain how a high waist-to-hip ratio might result in fatty deposits in a person’s arteries. In order to show that a high waist-to-hip ratio causes fatty deposits, scientists would need to explain how this could happen (to find evidence of a mechanism).

NOW look again at the learning outcomes for this activity.
Which learning outcomes have you achieved?
Which learning outcomes can you improve?