Question

1. Draw (with boxes and arrows) the design of a pretest-posttest within subjects/repeated measures experiment. The dependent variable is measured 3 times. Describe an experiment that you may conduct with this design. Explain the question that you are asking, what the pretest measures, what the dependent variable measures, and what independent variable or treatment you will use. Label each of these on the experiment design that you drew. Remember that with within subjects/repeated measure design the order can affect your results. How would you fix this? In a separate table from your drawing of the design, show specifically how you would fix this. What is the name for this method of fixing the order so it does not affect your results?

Answer 1

A pretest posttest design is a type of research design wherein the results from pre administration of a particular test/technique is noted and compared with the results, which will be obtained post administration. This research design helps eliminate the problem that is likely to arise from confounding variables, which can vitiate the results of the study, the only prerogative is to randomly assign subjects.

For the purpose of comprehension, a simple question can be probed by the aid of this design: New Teaching technique, and its impact (positive or negative) on the learning of the students.

The dependent variable would be the change in learning; and the Independent Variable would the teaching technique - by the application of which the dependent variable is affected.

Order effect, in simple language, is when performance of something in one condition has an affect on the performance in another due to the order that has been assigned by the investigator that is, first, second , third etc. This is especially a problem when the design consists of within subject sample, that is the subjects are the same throughout. The order affect that can possibly infiltrate the results of the aforementioned study would be the practice component. The students who have been randomly assigned to test the efficiency of a new teaching technique could perform relatively better - with respect to learning - by virtue of practice, and not owing to the actual efficacy of the teaching technique.

This problem could be fixed by the aid of application of the same order every time.This could be avoided by providing the subjects with an alternate warm up exercise before the application of the actual technique. So that the bias of the subjects cannot seep into the results of the study.