Chapter 10: Non and Quasi experimental designs

Question 1

What is the difference between Non and quasi experimental designs?

Answer 1

Quasi
- can control for confounds
- can use control group or multiple measurements
- keep internal validity high
—>otherwise non experimental

Question 2

What are the different non equivalent groups designs?

Answer 2

• Differential design→ Non experimental
• Post-test only NEG Design→ NE
• Pre-test/Post test NEG design→ Quasi
  -Cross sectional developmental-> NE

Question 3

What are the different pre-post designs?

Answer 3

-One group Pretest-posttest design-> NE
Longitudinal developmental-> NE
Time Series design-> Quasi

Question 4

Differential Design

Answer 4

Used in non experimental designs
- simplest NEG designs
- individuals differences are primary interests
- compared pre-existing groups to find a difference

Question 5

Post-test only NECG design

Answer 5

Used in non experimental
- used in applied research
- interested in effectiveness of treatment or intervention
- compare those who received treatment and those who did not
- two groups measured at same time

Question 6

Pre-test/Post-test NECG design

Answer 6

• try to add a bit of control with pre-test for both groups
  Limits threat to internal validity
• if similar at pre-test→ show that change probably comes from treatment and not from inherent difference between the groups

Question 7

One group pretest-posttest design

Answer 7

• over time measurement of one group of participants
• no control group
• cannot counterbalance order of treatments

Question 8

Time series design

Answer 8

• add some control by making a series of observations for each participants
• see the trend that existed before the treatment and how the trend change after the treatment
• can identify fatigue, maturation, instrumentation…
• can also look at non manipulated events→ data from archives
• at least 3 points needed
  –>External events can be confounding variables only if happens at same time as treatment

Question 9

Difference between level and trend

Answer 9

Level→ absolute value
Trend→ relative values changing

Question 10

What are the advantages and disadvantages of cross sectional designs?

Answer 10

Advantages
- Time-efficient→ don’t have to wait for people to get older
- No long term cooperation required

Disadvantages
- Cohort or generation effects→ changes due to time period
- individuals changes not assessed

Question 11

What are the advantages and disadvantages of longitudinal designs?

Answer 11

Advantages
- No cohort or generation effects
- Individual changes assessed

Disadvantages
- Time-consuming & costly
- Participant attrition can caused unbalanced measures
- Potential for practice effects over time (ex: use same version of test)