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Causal Comparative Research
Threats to Experimental Validity
Group Experimental Design
Analyze This Study!
100
Define Causal Comparative Research
Determining the cause for existing differences in the behavior of groups/individuals.
100
TRUE/FALSE Any uncontrolled extraneous variables that affect performance on the dependent variable are threats to the validity of an experiment.
True
100
When is a quasi-experimental design appropriate?
When it is not possible to assign participants to groups randomly.
200
Which causal comparative research would be more appropriate for educational purposes, retrospective or prospective?
Retrospective
200
What is the difference between internal validity and external validity?
Internal validity is the degree to which observed differences on the dependent variable are direct results of manipulation of the independent variable not some other variable. External validity is the degree to which study results are generalizable to groups and environments outside the experimental setting.
200
What is a factorial design used for in a study?
It is used to study whether the effects of an independent variable are generalizable across all levels or whether the effects are specific to particular levels. In other words, looks to see if the independent variable creates a main effect or there is an interaction.
300
What are effective ways to form groups in a causal comparative study?
Control Procedure
300
How can mortality, a threat to internal validity, affect your study?
Your study is less valid when participants drop out.
300
What does the Solomon four-group involve?
Random assignment of participants to one of four groups. Two of the groups are pretested and two are not; one of the pretested groups and one of the un-pretested groups receive the experimental treatment. Data comparison at post-test is made between all four groups.
400
TRUE/FALSE You should manipulate grouping variables in a causal comparative study.
False
400
Pre-test treatment, specificity, and generalizability are threats to what kind of validity?
External validity
400
What is the best way to analyze data resulting from the Solomon four-group design?
Use a factorial analysis of variance (factorial = a design with more than one independent variable)
500
• You plan a study to compare two methods, x and y, of teaching 5th graders to solve math problems. When you gave the two groups a math ability test before teaching the new methods, you found that the group to be taught by method y scored much higher than the group to be taught by method x. This difference suggests that the method y group will be superior to the method x group at the end of the study just because members of the group began with higher math ability. In order to make sure the results can be fairly compared, what would you do to the scores?
Adjust the scores according to analysis of covariance.
500
What is one way of controlling an extraneous variable?
To compare groups that are homogeneous with respect to that variable (OR) Form subgroups representing all levels of the control variable
500
Describe the differences between a one-group posttest-only design, one-group pretest-posttest design and two groups posttest-only design.
One-group posttest-only design: Involves one group that is exposed to a treatment and then tested. One-group pretest-posttest design: Involves one group that is pretested, exposed to a treatment, and tested again. Two groups posttest-ony design: Two nonequivalent groups compared at post-test only
500
Sketch a causal-comparative research study. State the RQ, IV, DV, H1, H0, possible errors, methods, expected results, and forms of data collection. Answers vary
Reminder: causal-comparative approach for a study means the researcher starts with an effect and seeks possible causes.