Download Dr Mariella H tier questions

H Qs
Dear Dr Mariella
Read the letter from Kerry to Dr Mariella, and look at the data supplied on the sheet.
Learning
Objective:
To learn about correlation and cause.
Learning
Outcomes:
All of you will be able to give an example from
everyday life of a correlation between two things.
All of you will be able to identify a factor that may affect
a person’s risk of heart disease.
Most of you will be able to recognise that even with
these factors it may still not happen.
Some of you will be able to explain that if someone
claims something is the cause of an outcome, that this
is more believable if there is also a good explanation
for the link between them (a mechanism).
1 What do scientists mean by a ‘correlation’?
2 Write down an example of a correlation from your everyday life.
3 In her reply, Dr Mariella says:
‘Just because there is a correlation between a bigger waist-to-hip ratio and
a bigger risk of heart disease, this does not mean that a bigger waist-to-hip
ratio causes heart disease.’
Explain how there could be a correlation between two things even though
one does not cause the other.
4 What correlation does the Dallas Heart Study data show?
5 In the data table from the Dallas Heart Study, the entry for group 1 in the
column ‘likelihood of fat in the arteries compared with group 1’ is 1.0.
Explain why this value is exactly 1.0.
© University of York and Nuffield Foundation 2009
C21 IaS2 KAT Dr Mariella H Qs page 1
H Qs
6
a In the Dallas Heart Study table, which group is Kerry in?
b Does this mean she will not suffer from heart disease later in her life?
Explain your answer.
7
a In the Dallas Heart Study table, which group is Kerry’s husband in?
b How much more likely is Kerry’s husband to suffer from heart disease
than Kerry?
8 Suggest how fat deposits in a person’s arteries may cause heart
disease.
9 Doctors recommend that men should have a waist-to-hip ratio of 0.9 or
less to have a lower risk of heart disease. Does this mean that Kerry’s
husband will definitely suffer from heart disease later in life? Explain your
answer.
10 Kerry’s husband says that his Dad is still alive and healthy. Does this
mean that Kerry’s husband will not suffer from heart disease in later life?
Explain your answer.
11 Scientists are trying to find out how having a high hip-to-waist ratio can
result in fatty deposits in a person’s arteries (a mechanism). Why is this
important?
© University of York and Nuffield Foundation 2009
C21 IaS2 KAT Dr Mariella H Qs page 2