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Evaluating Design Choice and Threats to Validity

Evaluating Design Choice and Threats to Validity in a Quasi-Experimental Design

Being a critical researcher requires practice and thought into the reasoning behind various research design choices. In this Discussion, you will consider a quasi-experimental design used from the attached study and evaluate it for its appropriateness and any potential flaws it has that may have impacted the research.

To prepare for this Discussion:

1. An evaluation of the choice of design and threats to validity in a quasi-experimental design.
2. An evaluation of the choice of design, the author's rationale for the design choice, the types of validity presented and the critical differences among them, and the author's performance in explaining them.
3. Assess the strengths and limitations of the research design presented.
4. Also, how you would assess the study's validity and the information you would require to do so.


Solution Preview

1. An evaluation of the choice of design and threats to validity in a quasi-experimental design.

In a quasi-experimental design, the research substitutes statistical "controls" for the absence of physical control of the experimental situation (i.e. as exposed to a true experiment in a laboratory). The most common quasi-experimental design is stated to be the Comparison Group Pre-test/Post-test Design (research methods). This design is similar to a controlled experiment; however, the subjects cannot be randomly (each subject has a chance of being selected) assigned to the control group or experimental group; or receive a treatment. In other words, participants do not all have the same chance of being in the control or the experimental groups, or of receiving or not receiving the treatment. Thus, the choice of quasi-experimental design is the "Comparison Group Pre-test/Post-test Design.

*Potential threats to Internal validity:

1) History: Did both groups experience the same current events, or was there a change in the dependent variable?
2) Maturation: If there were changes were the changes due to normal development processes. In this case, no, because these ae two mature adults.
3) Statistical Regression: Did subjects come from low or high performing groups? (Were socio-economic conditions a factor?).
4) Selection: were the subjects self-selected into experimental and control groups, which could affect the dependent variable?
5) Experimental Mortality: Did some subjects drop out? Did this ...

Solution Summary

This solution discusses the evaluation of quasi-experimental designs