Research Designs

Question 1

Between subjects design

Answer 1

• subjects are randomly assigned to independent groups
• compared between groups
• experimental design

Question 2

Within subjects design

Answer 2

• subjects act as their own control
• no true experimental design

Question 3

Single factor design vs multi-factor design

Answer 3

• single factor design has one IV (# of levels are 2 or great to compare between groups)
• a multi-factor design has 2 or more IV

Question 4

Explanatory (experimental design)

Answer 4

• evaluate cause and effect relationship between independent variables and dependent variables
• research manipulates levels of independent variable
• ex: randomized controlled trials and pragmatic clinical trials

Question 5

Pretest-Posttest control group designs

Answer 5

• basic structure of randomized controlled trials (RCT)
• groups assigned at random
• differ only on basis of what occurs between measurements
• can also involve more than 2 groups

Question 6

What is the validity of a pretest-posttest group design
- What does each part provide to validity
- primary threat to validity

Answer 6

• internal validity is strong
• pretest scores: establish initial equivalence of groups and evidence for intervention causing group differences in posttest scores
• history, maturation, testing, instrumentation effects –> affect all groups equally in both pretest and posttest
• primary threat to validity: interaction of treatment and testing (might have a treat affect from the pretest)

Question 7

Describe Posttest only control group design

Answer 7

• identical to pretest-posttest design
• without pretest
• used when a pretest is either impractical or potentially active

Question 8

Posttest only control group design- validity

Answer 8

• internal validity is strong (not as strong as RCT)
• assume groups are equivalent prior to treatment (random assignment)
• most successful when large number of subjects are used
• increase probability of balancing interpersonal characteristics

Question 9

Factorial Designs- independent groups
- how are the described and assigned

Answer 9

• 2 or more IVs
• independent groups of subjects; randomly assigned to various combinations of levels of variables
• described according to # of factors (IVs)
• 2 way: 2 IVs
• 3 way 3 IVs

Question 10

What is main effect vs interaction effect in Factorial Designs- independent groups

Answer 10

• main effect: effect of each IV independently
• interaction effects: when effect of one variable varies at different levels of a second variable – an effect caused by an interaction

Question 11

How do you describe Factorial Designs- independent groups

Answer 11

• # of facts and #of levels for each factor
• 3x2 = 2 factors (IVs) and fact 1 has 3 levels and factor 2 has 2 levels

Question 12

repeated measures design

Answer 12

• one group of subjects tested under all conditions
• each subject acts as own control
• advantage:
• control for potential influences of individual differences
• should only be used when outcome measure will revert back to baseline between interventions
• ransoms order of interventions increases validity
• not appropriate with variables that produce long-term effects

Question 13

carry over effects in repeated measure design

Answer 13

• disadvantage of repeated measures designs
• cary over effects:
• when one subject is exposed to multiple treatment conditions
• control: allotting time between successive treatment conditions
• allow for dissipations of previous effects

Question 14

practice effects or order effects of repeated measures design

Answer 14

• another disadvantage
• practice effects:
• learning effects that can occur when individual repeats a task over and over
• control: randomize order of trials