Week 3: Quasi-Experimental Designs
Week 2 introduced experimental designs as the best way to logically reject or fail to reject a null hypothesis, but there are many situations in which an experimental design is not applicable; for instance, when a researcher cannot control one or more of the variables in the study, or when an experimental design is not appropriate due to social, political, and ethical considerations. In these situations, the quasi-experimental design is often employed by social science researchers as a method to gain valid information.
This week, you will evaluate a quasi-experimental design presented in a study from your discipline, after which you will use your knowledge of experimental and quasi-experimental designs to select and justify the proper research design for your own research plan. In addition to selecting and justifying a research design, you will continue to analyze the threats to validity inherent in each design. This work contributes to the Final Project.
By the end of this week, you should be able to:
- Evaluate the choice of design and threats to validity in a quasi-experimental design
- Assess the strengths and limitations of quantitative research designs
- Recommend a research design for a quantitative study
- Course Text: Research Methods in the Social Sciences
- Chapter 8, "Sampling and Sample Designs"
Chapter 8 covers the purpose, methods, and execution of sampling, as well as how to determine the appropriate sample size for your research. This resource is used in this week's Discussion and Application.
- Appendix D, "Random Digits"
Appendix D is a table of random digits you may use in a research design to randomize the groups in your sample. This resource will be useful in this week's Application.
- Handout: Research Articles (Word document)
This handout provides articles chosen by your program that you will use for this week's Discussion. Locate your program within the document to find the article you should use.
- Handout: Sample Size Analysis for Quantitative Studies (PDF document)
This document elaborates on analyzing sample sizes in a quantitative study and includes tables that suggest appropriate sample sizes for statistical tests you might conduct during your research. This resource will be useful for the Discussion and Application this week.
- Website: Buchner, A., Faul, F., & Erdfelder, E. (n.d.) G*Power. Retrieved June 30, 2014, from http://www.gpower.hhu.de/
The G*Power website explains the purpose and features of G*Power and allows users to download the program.
Downloading any software from a site that is not the official site of the software creator can cause issues. There are a variety of sites from which you can download G*Power, beyond the one provided in this course. These sites are safe. However, the software that is bundled with the installers can be more or less annoying, and can often introduce you to additional (harmless) software. This software should not be mistaken for viruses. In fact, if you are very careful, you can completely avoid installing any other software, but to do that, you must read carefully every screen that is presented in the installation process. In the case of G*Power, you can avoid any problems by downloading the software from the original site: http://www.gpower.hhu.de/
- Course Text: Publication Manual of the American Psychological Association
- Chapter 3, "Writing Clearly and Concisely"
- Chapter 4, "The Mechanics of Style"
- Chapter 6, "Crediting Sources"
- Chapter 7, "Reference Examples"
- SPSS Technical Support
The SPSS online student support site provides a knowledge base and assistance from SPSS Technical Support staff.
- DSS Research: Sample Size Calculator
This calculator can help you determine what the sample size of a project will need to be.
- Sample Size Calculator: The Survey System
This Sample Size Calculator is presented as a public service of Creative Research Systems. You can use it to determine how many people you need to interview in order to get results that reflect the target population as precisely as needed. You can also find the level of precision you have in an existing sample.
- DSS Research: Sample Error Calculator
This tool allows you to calculate the sampling error for any sample.
- See the Suggested Bibliography for recommended books.
Discussion - Week 3
Top of Form
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 in a study within your discipline and evaluate it for its appropriateness and any potential flaws it has that may have impacted the research.
To prepare for this Discussion:
- Review Chapter 6, "Research Designs: Cross-Sectional and Quasi-Experimental Designs" in Research Methods in the Social Sciences.
- Review the assigned article for your program within the Research Articles document located in the Learning Resources. Evaluate the choice of the design used in the assigned article. Why was that design used and not another one? Assess the authors' performance in explaining this.
- What are the types of validity presented and the critical differences among them? Assess the authors' performance in explaining them.
- How would you assess the study's validity? What information would you need in order to be able to do, and is that information present in the article?
With these thoughts in mind:
Post by Day 3 a 3-paragraph evaluation of the choice of design and threats to validity in a quasi-experimental design. Your response should include 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, the author's performance in explaining them, and how you would assess the study's validity and the information you would require to do so.
When appropriate, be sure to support your postings and responses with specific references to the reading(s) and/or video program(s) and use APA format.
True experimental designs are often unrealistic in implementation and may have serious ethical issues. Therefore, quasi-experiment deisgns are widely used in social and behavioral research studies. Here is the link to a useful summary of various kinds of quasi-experimental designs: http://condor.depaul.edu/dallbrit/extra/psy242/242-QUASI.HTM - Dr. Yu
|Due By (Pacific Time)
||06/18/2015 08:20 am