Four Types of Validity in Quantitative Research
When researchers determine whether their results can be trusted, there are two important issues that should be considered. One is external validity, which is the validity of generalizing the sample data to a population, and the other is internal validity, which involves the extent to which the dependent variable can be credited to changes in the independent variable.
In experimental research, the researcher manipulates at least one independent variable (such as the hypothesis/cause) then attempts to control any potential confounding variables, and then measures the effect(s) on one or more of the dependent variables. Validity helps us to determine that if these steps are taken – if the researcher is following the rules of internal and external validity.
Therefore, internal validity is important for studies that attempt to determine cause-and-effect – it helps us determine if a treatment, intervention, or program made a difference. Internal validity means that the researcher has evidence that what was done in the study (i.e., intervention) caused what the researcher observed (i.e., the outcome) to happen (Research Methods Knowledge Base).
External validity assumes that there is a causal relationship in a study between the constructs of the cause and the effect, and that the research can generalize this effect to other persons, places or times (Trochim, 2008).
The four validity types (conclusion validity, internal validity, construct validity, and external validity) build upon one another. In this sense they are cumulative as seen in this diagram.
Be sure to review this week’s resources carefully. You are expected to apply the information from these resources when you prepare your assignments.
All resources for this week:
Jackson, S. L. 2016 Research methods and statistics: A critical thinking approach.
Read Chapter 9 (pages 235-244)
Trochim, T.M., Donnelly, J., & Arora, A. 2015 Research methods: The essential knowledge base.
Read Chapter 3 (pp. 67-71),Chapter 5 (pp.127-140),Chapter 9 (pp. 234-235), & Chapter 11(pp. 281-287)
Internal Validity. Web Center for Social Research Methods. http://www.socialresearchmethods.net/kb/intval.php
Introduction to Validity.Web Center for Social Research Methods. http://www.socialresearchmethods.net/kb/introval.php
Reliability and Validity http://wadsworth.cengage.com/psychology_d/templates/student_resources/workshops/res_methd/reli_vali/reli_vali_01.html
Locate Research Articles
This week you will locate at least five research articles to support your Week 10 assignment, which will have you charting and describing the major threats to validity for conclusion, construct, and external validity, and explaining how you would minimize them for internal validity.
Length: 5 references
You do not need to submit any documents this week.
Course Learning Outcomes associated with this assignment:
1.0. Identify the types of quantitative research design.
4.0. Examine validity and threats to validity in quantitative designs.
5.0. Evaluate aspects of quantitative designs.