Case Control Studies

Question 1

Case-Control Study

Answer 1

Identifying people who are already ill with outcome and people who are not ill (They are the case controls)

These people are then compared to explore factors which may contribute to difference in disease status

Looks backwards in time to compare exposure to risk factors

**e.g. whether smoking increases risk of lung cancer

Question 2

Stages of Case-Control Study

Answer 2

Define a Case and Control Group

Sample the cases and controls

Collect Exposure Data

Analyse/Interpret Data

Question 3

Selection bias in case control study

Answer 3

Cases and controls are not representtative of people with and without the disease

Should both be from the same population

Question 4

Biases in collecting data during case control studies

Answer 4

Recall Bias - Selective memory (e.g. smokers having better recollection of smoking habits if diagnosed with lung cancer)

Response Bias - Participants respond the way they think they are expected/wanted to respond

Interview Bias - Interviewer is biased if they knew whether participant is case or control

Question 5

Odds Ratio

Answer 5

**OR=2.97 means that people with lung cancer are almost 3 times more likely to be smokers than people without Lung Cancer