Chapter 13: Quasi-Experiments & Small-N Designs

Question 1

Quasi-Experiment

Answer 1

Differ from true experiments because researchers do not have full experimental control
Select an independent and dependent variable
Hope to support a causal claim
May not be able to use random assignment
Try to carefully select two or more groups that only differ on the IV

Question 2

Quasi-Independent Variable

Answer 2

Researchers do not have full control over this variable
E.g. Two default consent options for organ donation (opt in/opt out consent)

Question 3

Small-N Designs

Answer 3

Obtain a lot of information from just a few cases
Still useful and valuable when done correctly
Allows study of unique cases
E.g. Phineas Gage, patient HM, Piaget’s developmental stages

Question 4

Disadvantages of Small-N Studies

Answer 4

Brain damage is not usually restricted to one area
Poor external validity

Question 5

Behaviour-Change Studies

Answer 5

Stable baseline designs
Multiple baseline designs
Reversal designs

Question 6

Stable Baseline Designs

Answer 6

Observe behaviour for extended baseline period before beginning a treatment/intervention
Stable behaviour prior to intervention indicates treatment’s later effectiveness
E.g. assess memory of Alzheimer’s patient before teaching a new rehearsal technique
Increases internal validity by ruling out some alternative explanations

Question 7

Multiple Baseline Designs

Answer 7

Stagger introduction of intervention across a variety of individuals, times, situations to rule out alternative explanations
See if all individuals show stable baselines and only improve after treatment
Observing similar patterns in multiple participants rules out other explanations
Can support a causal conclusion, increases internal validity

Question 8

Reversal Designs

Answer 8

Observe a problem behaviour both with and without treatment, but take treatment away for a while (reversal period) to see if problem behaviour returns (reverses)
Reintroduce treatment after reversal to see if behaviour improves again
Appropriate for situations where a treatment may not cause a lasting change
Wouldn’t work for educational interventions (once learn skill don’t unlearn it)
Can be considered harmful/unethical to withdraw effective treatment