Replication, Generalization, and External Validity

In the Discussion for this week, you addressed one of the threats to the internal validity of a study, that is, confounding variables. This Application Assignment will challenge you to consider possible threats to external validity. Generalization is the extent to which relations among variables in research studies can be demonstrated among a wide variety of people and across different settings. When the results of a research study are generalizable to additional populations and settings, the study demonstrates external validity. However, if a research study is only valid for the particular sample used in the study, then it is not very helpful to the study of psychology.
In the example provided in the Discussion introduction, two online student groups used different study strategies. Now imagine a human resource (HR) manager at a corporation, struggling with the concept of reading comprehension among employees in the workplace setting, wanted to try the new study strategy that the online course instructor had researched. Assume that the online college course instructor had resolved possible issues relating to internal validity and found that the new study strategy was effective at improving reading comprehension. The HR manager presumes that the results of the study with online college students will generalize to her training course at work. However, the replication of the study revealed that, although the new strategy was found to work well for online students, the results did not generalize to the training course in the work setting. Therefore, the original study lacks external validity.
Replications of studies, such as the one in this example, are essential to demonstrate generalization and external validity. This week, you will learn about four types of replication procedures, and you will develop original examples of each procedure with the goal of demonstrating generalization and external validity.
To prepare:
Review Chapter 13 from the course text.
The Assignment (1?2 pages):
Explain the four different types of replications and the purpose of each. Include for each type of replication a brief original psychological study example (i.e., make up your own) that is different for each type of replication (i.e., do not build on the same example). Plan to devote a short paragraph for each.
Briefly explain how replications relate to the concepts of generalization and external validity.