Formative

Question 1

Definition of a confounding variable

Answer 1

A variable which affects both the exposure and outcome

Question 2

What type of data is blood group?

Answer 2

Nominal

Question 3

A retrospective study comparing prior exposures in patients with a disease outcome to patients without is a:

Answer 3

Case-control study

Question 4

The odds ratio of recurring diarrhoea in a probiotic drink group compared to a placebo group was 0.45 (p<0.05).

Answer 4

There was a 55% reduction in odds following the probiotic drink

Question 5

A study was set up to test the diagnostic accuracy of a new test.
Sample of 100 people- 25% who have disease, After using new testing method 30 were flagged as being positive- of which 20 actually had the disease.

What is the specificity and sensitivity of this study?

Answer 5

Specificity= 86% Sensitivity= 80%

100-30=70 negative tests
25-20= 5 true positives that are negative
70-5= 65 negatives that are negative
65/75= 86.67% specificity

20/25= 80% sensitivity

Question 6

Sensitivity

Answer 6

Likelihood of a positive person by test being positive

Question 7

Specificity

Answer 7

Likelihood of a negative person by test being negative

Question 8

Neha, a student living it large in Tanzania, wants to investigate the risk factors for Creutzfeldt-Jakob disease (rare type of dementia) by interviewing patients diagnosed in the past 5 years. Which study model type would be most suitable?

Answer 8

Case control