Pros and Cons of Study Types

Question 1

Strengths of RCTs?

Answer 1

Randomisation reduces confounding.

You have control over what is studied and the outcome

Question 2

Strengths of Cohort studies? (4)

Answer 2

Temporal relationship
Exposure accurately measured
Data on confounding
Incidence rates measured.

Question 3

Weaknesses of case control studies? (4)

Answer 3

Temporal relationships are unclear
Bias
Confounding
Can’t measure incidence

Question 4

Weaknesses of RCTs? (5)

Answer 4

Ethics difficult
Expensive
Time-consuming
Short time scales
Very specific population

Question 5

Strengths of case control studies? (4)

Answer 5

Captures rare outcomes
Relatively cheap and quick
Able to explore many different exposures
Good for diseases that take a long time to develop

Question 6

Strengths of cross-sectional studies? (5)

Answer 6

Data readily available - quick and cheap
Answers particular question
Few ethical considerations
Estimates of prevalence for all variables measured
Findings are generalisable (if sampling random)

Question 7

Weaknesses of cohort studies? (5)

Answer 7

Time consuming and expensive
Collecting data might change an individual’s behaviour
Can’t collect more info afterwards - confounders
Diagnostic techniques or definitions might change during follow-up period.
Biases

Question 8

Strengths of ecological studies? (6)

Answer 8

Quick and cheap
Data readily available
Few ethical considerations
Explores a number of possible associations at one time
Can identify associations not previously considered
Generates hypotheses

Question 9

Weaknesses of ecological studies? (4)

Answer 9

Causality cannot be inferred because the group of people described by the disease data are not the same people as those described by the exposure data.
Temporal relationships unclear
Subject to confounding
Selection and information bias.

Question 10

Weaknesses of cross-sectional studies? (3)

Answer 10

Temporal sequences can’t be established.
Omission of difficult to identify individuals
Selection and information bias