Lecture 9: Quasi-Experimental Designs

Question 1

What differentiates a quasi-experimental design compared to a basic experimental design?

3pts

Answer 1

• Quasi-experimental designs resemble experimental designs but lack either a comparison group or
  random assignment across conditions
• Compared to experimental designs, quasi-experimental designs are lower in internal validity, but may be higher in external validity
• Cannot determine causal influence

Question 2

When do researchers use quasi-experimental designs?

Answer 2

Researchers use quasi-experimental designs when using an experimental design would be either
impractical, impossible, or unethical.

Question 3

Threats to internal validity: A historical event (e.g., natural disaster, media event) affects all or most participants and that is not of interest

a. Maturation
b. Testing
c. Selection effects
d. Attrition
e. history
f. cohort effects

Answer 3

History

Question 4

Threats to internal validity: Natural changes to participants’ short-term states
(e.g., fatigue) or long-term development (e.g.,
education) that are not of interest.

a. Maturation
b. Testing
c. Selection effects
d. Attrition
e. history
f. cohort effects

Answer 4

Maturation

Question 5

Threats to internal validity: Extreme scores tend to become less extreme on repeated measurement; may occur when participants are chosen based on extreme scores on a pretest

a. Maturation
b. Testing
c. Selection effects
d. Attrition
e. history
f. cohort effects

Answer 5

Testing

Question 6

Threats to internal validity: Participants leave the study before its completion.

a. Maturation
b. Testing
c. Selection effects
d. Attrition
e. history
f. cohort effects

Answer 6

Attrition

Question 7

Threats to internal validity: Groups are divided for any reason other than random assignment

a. Maturation
b. Testing
c. Selection effects
d. Attrition
e. history
f. cohort effects

Answer 7

Selection effects

Question 8

Threats to internal validity: Groups are divided by age (a special case of selection effects)

a. Maturation
b. Testing
c. Selection effects
d. Attrition
e. history
f. cohort effects

Answer 8

Cohort effects