Week 3

Question 1

Learning outcomes:

Answer 1

• Describe what an experimental design is
• Explain the core aspects of a randomised controlled trial and associated concepts
• Assess a paper in relation to components of an RCT

Question 2

Double blinding

Answer 2

: neither participant nor
researchers know who is in what group
desirable but not always possible.

Question 3

What should the control group receive

Answer 3

Plaecbeo, or fair comparison (think testing a new diabetes drug and giving control regular insulin)

Question 4

What are the three aspects of an RCT?

Answer 4

Randomization, control, manipulation

Question 5

When RCT are “right”

Answer 5

The only research design that can test the cause and effect of treatments with a high degree of certainty

Question 6

Flaws with RCT

Answer 6

• Over-reliance on RCTs and discounting other evidence/ knowledge
• May not answer the questions of how and for whom a certain treatment is best
• Some interventions cannot and should not be verified by RCTs (for ethical and pragmatic reasons)
• Transferability to other populations
• Even field tests may not represent true behaviour (Hawthorne effect)
• Complex interventions
• Consider mixed methods/ embedded process evaluations

Question 7

Confounding

Answer 7

A confounder is a variable that influences both the dependent variable and
independent variable, causing a spurious association; hence correlation does not imply
causation. Often a problem with uncontrolled experiments

Question 8

Clinical equipoise

Answer 8

There is not one “better” intervention present during the design of an
RCT. A true state of clinical equipoise exists when one has no good basis for a choice
between two or more care options/ interventions. It provides an ethical basis for RCTs.

Clinical equipoise means that there is genuine uncertainty in the expert medical community over whether a treatment will be beneficial. Equipoise provides the ethical basis for randomized controlled trials.

Question 9

Intention to treat

Answer 9

: refers to the analysis of the results of an experiment is based on the initial
treatment assignment and not on the treatment eventually received.

Question 10

Hawthorne effect

Answer 10

: participants modify their behaviours because they are aware of being
watched/ observed. It can also contaminate an intervention study if one of the control
groups changes its behaviour because it is being observed more frequently than the other.

Eg: A study of hand-washing among medical staff found that when the staff knew they
were being watched, compliance with hand-washing was 55% greater than when they
were not being watched (Eckmanns 2006).

Question 11

Loss to follow up

Answer 11

participants who at one point in time were actively participating in a
clinical research trial, but have become lost (either by error in a computer tracking system
or by being unreachable) at the point of follow-up in the trial.

Question 12

quasi experiment

Answer 12

a research design in which the researcher initiates an experimental treatment, but some characteristic of a true experiment is lacking. Control may not be possible because of the nature of the independent variable or the nature of the available participants. Quasiexperimental designs usually lack the element of randomization

Question 13

Why would a quasi-experiment be used over a regular experiment?

Answer 13

Researchers frequently use quasiexperimental designs to test cause-and-effect relationships because experimental designs are often impractical or unethical