Experimental Design Flashcards
What is the difference between internal and external validity?
Internal validity is finding out if the change in dv finding out if the dv is caused by the change in the iv.
What are the common threats to internal validity?
-Sampling bias -Instrumentation/Measurement -Data collection time -Diffusion/Equalization
What are the threats to external validity?
-Laboratory isn’t like the real world -Participants not typical of general population -Behavior isn’t typical of participants
What can be done to increase internal validity?
-Maximize systematic variance -Minimize error variance -Control extraneous systematic variance
What can be done to increase external validity?
-Use representative sample -Replicate the study -Use triangulation
Can a study have external validity if it doesn’t have internal validity?
No internal validity is a precondition to external validity. You must have internal validity to have external validity.
Can a study have internal validity without external validity?
Yes you can have internal validity without external validity
What is an experiment?
studies the effects of a manipulated variable on a 2nd variable, while controlling for all other sources of influence on the 2nd variable.
What is pre-testing?
Pre-test happens before you manipulate the IV
What is post-testing?
“happens after you manipulate the IV. Also to - To compare variation in DV before and after treatment”
what is the difference between a treatment group and a control group?
Experimental group receives “treatment” and is compared to control group (no treatment)
When should a researcher use an experimental design?
- when the research goal is explanation
- to determine cause-effect relationships
Pre-test, Post-test, Control Group?
- First Group: Pretested, exposed to the experimental variable, and post tested
- Second Group: Pretested, NOT exposed to experimental variable, and post tested
What is the Soloman Four group?
Experiment with 4 groups
- pre-test, treatment, post-test
- pre-test, no treatment, post-test (control group)
- treatment, post-test
- post-test only
Rules out the influence of “testing effects” and “time effects”
What is the Post test only group group?
- First Group: exposed to the experimental variable and then post tested
- Second Group: not exposed to the experimental variable and then post tested
