Types of Bias

Question 1

A to H (3)

Answer 1

Allocation
Attrition
Hawthorne

Question 2

M to P (4)

Answer 2

Maturation
Measurement
Natural progression
Placebo

Question 3

R to V (4)

Answer 3

Regression to the mean
Rosenthal
Selection/sampling
Volunteer

Question 4

Allocation bias?

Answer 4

Different baseline between groups (RANDOMISE)

Question 5

Attrition bias?

Answer 5

Patients withdraw from study

• MINIMISE LOSS TO FOLLOW UP
• ITT

Question 6

Hawthorne effect?

Answer 6

Change from attention received (CONTROL)

Question 7

Maturation bias?

Answer 7

Pt matures over time (esp children)

• CONTROL
• RANDOMISE

Question 8

Measurement bias?

Answer 8

Errors
- expectations of pts/therapists/researchers

• BLINDING

Question 9

Natural progression?

Answer 9

Disease/condition natural ly improves over time

- RANDOMISE

Question 10

Placebo effect?

Answer 10

Pts expect to get better

• SHAM
• BLINDING

Question 11

Regression to the mean

Answer 11

Outliers are less likely to be outliers when reassessed

• RANDOMISE
• CONTROL

Question 12

Rosenthal effect?

Answer 12

Pts perform better because they are expected to

• SHAM/BLINDING
• RANDOMISE

Question 13

Selection/sampling bias?

Answer 13

Those sampled are different from those not selected (can’t generalise to population)
- GOOD SAMPLING

Question 14

Volunteer bias?

Answer 14

Systematically different people who volunteer

• RANDOMISE
• CONTROL