Study Design

Question 1

What are the two categories of methods of sampling?

Answer 1

Random and non-random

Question 2

What must the sample do to be externally valid?
What is bias?

Answer 2

Sample must represent population of interest

Bias - certain subgroups from the sample are over/under represented in the sample

Question 3

When does bias arise?
How does it impact results?

Answer 3

Arises when imperfections in the research cause the findings to deviate from the truth

Impacts validity and reliability of study findings and can distort results

… so it must be considered in critical evaluation of results

Question 4

Name 5 different types of bias

Answer 4

Sampling/selection bias
Recall bias
Information bias
The “Hawthorne” effect
Attrition bias

Question 5

What is sampling/selection bias?

Answer 5

Sample does not represent population of interest

Question 6

What is recall bias?

Answer 6

inaccurate recall of past events/exposures/behaviours

Question 7

What is information bias?

Answer 7

incorrect measurements of information

Question 8

What is the “Hawthorne” effect?

Answer 8

participants change their behaviour when they know they are being observed

Question 9

What is attrition bias?

Answer 9

differential dropout from studies e.g. sicker participants drop out so outcome only measured on healthier participants