1. Types of Designs: R: Random Assignment of subjects to groups
O: Observation or test
T: The treatment applied (T1, T2 on different lines refer to different treatments; terms on same line mean treatment is administered more than once)
--- A dotted line between groups means that the groups are used intact rather than being randomly formed.

2. Preexperimental Designs:
Controls very few sources of invalidity.
No Random assignment of subjects.
Not valid means to answer research questions.
Change in dependent variable cannot be attributed to the manipulation of the independent variable.

3. One Shot Study: T O
Very Poor Design

4. One-Group Pretest-Posttest Design O1 T O2
Weak, but can observe if a change in performance has occurred. Can’t show why subjects improved.

5. Static Group Comparison: T O1 O2
Groups are not equivalent before study began. (Often intact groups used)
Problems with selection biases and selection-maturation interaction.

6. True Experimental Designs:
Groups are randomly formed; assumption that they were equivalent at the study’s beginning.

7. Controls For: History (past not present)
Maturation (should occur equally in both groups)
Testing
Invalidity based on statistical regression, selection biases, selection-maturation interaction

8. Randomized Groups Design:
R T O1 R O2 Can be extended to any number of levels. R T1 O1 R T2 O2 R O3

9. Pretest-Posttest Randomized Groups Design
R O1 T O2
R O3 O4
Determines the amount of change produced by the treatment.
Threatens internal validity of testing.
Controlled by O1 to O2 and O3 to O4

10. Solomon Four-Group Design
Only true design to evaluate reactive or interactive effects of testing.
R O1 T O2
R 03 O4
R T O5
R O6

11. Quasi-Experimental Designs:
Designs in which the researcher tries to fit the design to more real-world settings while controlling as many threats to internal validity as possible.

12. Time Series:
Has only one group but attempts to show that the change that occurs when the treatment is interjected differs from the times it is not. O1 O2 O3 O4 T O5 O6 O7 O8 May control for selection bias, maturation (history, instrumentation, mortality researcher must control)

13. Reversal Design:
Purpose is to determine baseline measures, evaluate treatment, return to baseline, evaluate treatment, and return to baseline. O1 O2 T1 O3 O4 T2 O5 O6

14. Nonequivalent Control Group
Used in real world settings where groups cannot be randomly formed. O1 T O2 O3 O4

15. Ex Post Facto Design
Same as design 3, but Treatment not under control by the experimenter T O1 O2

16. Switched Replication Design:
Can be true or quasi depending on whether levels are subjects or groups. Levels (Subjects Trials or groups) O1 T O2 O3 O4 O5 2 O6 O7 T O8 O9 O10 3 O11 O12 O13 T O14 O15 4 O16 O17 O18 O19 T O20