Experimental Design

Quiz 4

design classifications

1. experimental design

2. quasi-experimental design

experimental design consists of…

• randomization

• control group

quasi-experimental design consists of…

doesn’t include random assignment or control group

types of randomization

• btwn-subjects design

• w/in-subjects or repeated measures

btwn-subjects design

• true randomization

• independent groups

• outcome assessment is the same (DV)

w/in-subjects or repeated measures

• subjects act as their own controls

• way to control subject variability

single factor design or 1 way design

1 IV w/ any number of levels

multiple factor design

• 2 or more IV

• described according to the number of IV

• may also incorporate the number of levels

• factorial designs can be shown via matrix table

Questions to consider in selecting a design

1. how many IV are being tested

2. how many levels does each IV have, & are these levels experimental or control conditions?

3. how many groups of subjects are being tested?

4. how will subjects be assigned to groups?

5. how often will “observations of responses” measurements be made?

6. what is the temporal sequence of interventions & measurements?

4 main designs

1. pretest-posttest control group

2. posttest only control group

3. factorial design for independent groups

4. repeated measures