1. Types of Group Designs
____________ group design. The experiment compares groups that receive or _______________ the IV (control group)
e.g., behavior is studied in 2 groups who have been given a medium dose of alcohol or placebo
Control group is the _______________group
Control group rules out internal validity threats
Participants should be randomly __________ from the population (if possible)
Participants in the sample should be randomly __________________ to groups or matched to prevent assignment bias
Lect 11a

2. When would you want to use a control group design?
Control group designs are used when:
You want a comparison group that does ____receive any level of the IV
e.g., the effects of hormones on aggression. Ovary removal in lizards.
Common in clinical studies where a new ______________ is being investigated
e.g., the effects of new drug on weight loss.
Lect 11a

3. Control-group Design Sample Drawn Randomly from Population
Random Assignment of Participants to Conditions IV
NO IV (Control)
Measurement of the Dependent Variable
Measurement of the Dependent Variable
Lect 11a

4. What does comparing to a control group tell us?
Post-test
Pre-test
Conduct
Experiment
Functional Relationship?
Lect 11a

5. What does comparing to a control group tell us?
Post-test
Pre-test
Conduct
Experiment
Functional Relationship?
To demonstrate a functional relationship, the experimental group should show a change but the control group should ______________.
This rules out the possibility that ________________ caused the effect.
Lect 11a

6. Types of control groups
_______________
________ control group – participants led to believe they are receiving some treatment although they are not.
(placebo = pharmacologically _______ substance)
________ control – those in control group eventually given treatment. Used in research designed to assess the effectiveness of treatment program.
Control group receives ________________, other group receives experimental treatment
Lect 11a

7. Control-group designs
Common control-group designs
____________ control group design
___________ control group design
____________ group design
Lect 11a

8. Pretest-Posttest Control-Group Design
Lect 11a

9. Pretest-Posttest Control-Group Design
Pre-test – provides some info about group ____________
Data analysis: pre vs. pre / post vs. post
________________ on control group allows you to rule out internal validity threats: history, maturation, regression
if they were affecting behavior, the control group should also show an effect
Disadvantage: _________ threat
Lect 11a

10. Posttest-Only Control-Group Design
Lect 11a

11. Posttest-Only Control-Group Design
Used when pre-tests are __________ or when they might ____________treatment (testing threats)
Data analysis: post vs. post
Threats to internal validity (maturation, history, instrumentation reduced by control group because their effects should be _______ in both groups)
Disadvantage: cannot determine group ____________
Lect 11a

12. Solomon Four-Group Design
Lect 11a

13. Solomon Four-Group Design
_____ groups
Combines _____________ and __________ designs
Controls for __________ threats - allows you to see what effects testing has on behavior
Data analysis: Multiple comparisons
pre vs. pre
post vs. post
pre vs. post, etc...
Disadvantage: many groups – study requires_____ subjects and is more difficult to conduct.
Lect 11a