Week 13

Question 1

What is selection bias and how can it be controlled?

Answer 1

Systemic differences between baseline characteristics (usually demographics) of the groups that are compared
Can be controlled by randomisation

Question 2

What is performance bias and how can it be controlled?

Answer 2

Systemic differences between the care that is provided

Can be controlled by blinding

Question 3

What is detection bias and how can it be controlled?

Answer 3

Systemic differences between groups in how outcomes are determined, such as overreporting adverse events
Can be controlled by blinding

Question 4

What is attrition bias and how can it be controlled?

Answer 4

Systemic differences between groups in withdrawal from a study
Can be overcome by making sure the intervention can be tolerated and mitigation should be looked into in a trial design

Question 5

What are the two types of observer bias and how can it be controlled? (4)

Answer 5

Observer bias is the failure to measure or classify exposure or outcomes appropriately
- Interview bias: investigator is aware of the treatment/ placebo
- Recall bias: participant selectively reports events because they know if they are taking the IMP or not
Can be controlled by blinding