Unit 8: Experimental Research

This unit contains the following sections:

8.1 Preface
8.2 Learning Outcomes
8.3 Introduction to Research Design
8.4 References

8.1 Preface

According to Neil J. Salkind (2003),

In scientific research, an experiment . . . is a method of investigating causal relationships among variables, or to test a hypothesis. An experiment is a cornerstone of the empirical approach to acquiring data about the world and is used in both natural sciences and social sciences. An experiment can be used to help solve practical problems and to support or negate theoretical assumptions. . . .

An experiment or test can be carried out by using the scientific method. The steps are make an observation, ask a question, form a hypothesis, test the hypothesis, analyze the results, draw a conclusion, and communicate results. The reason a hypothesis is tested is so that it can be confirmed, denied, or refined, with the knowledge currently available. The test has one variable. The control is the regular group and experimental is the group with the variable added to it.

To demonstrate a cause and effect hypothesis, an experiment must often show that, for example, a phenomenon occurs after a certain treatment is given to a subject, and that the phenomenon does not occur in the absence of the treatment. . . .

A controlled experiment generally compares the results obtained from an experimental sample against a control sample, which is practically identical to the experimental sample except for the one aspect whose effect is being tested (the independent variable). (Titi Tudorancea learning Center, 2010, emphasis in original)

[T]he simplest experimental design would be one [in which] two groups of subjects are randomly selected from a population and one group (the experimental group) receives a treatment and the other group (the control group) receives no treatment. At the end of the experiment, both groups are tested to see if there is a difference on a specified test score. Assuming . . . that the two groups were equivalent from the start of the experiment, any observed difference at the end of the experiment must be due to the treatment. That is what experimental design . . . is all about. (p. 224)

We anticipate that you will need about 10 hours (600 minutes) to complete this unit.

8.2 Learning Objectives

After completing Unit 8, you should be able to

describe the types of experimental research design.
identify an experimental research design appropriate for a given research plan.

8.3 Introduction to Research Design

We estimate that this segment of Unit 8 should take about 10 hours (600 minutes) to complete.

Viewing Assignment 8.3.V1

The video below provides an introduction to research design:

Campbell, L. (2010). Research design: An introduction. Retrieved from http://www.youtube.com/watch?v=-VoLWmE-vbI

The following is a short video by ‘headlessprofessor’ that introduces four designs to test a hypothesis: sample versus norms, repreated measures, separate groups, and correlational:

headlessprofessor. (2008). Research designs. Retrieved from http://youtu.be/FpHee7l1cZg

Reading Assignment 8.3.R1

This reading provides discussions of various, mostly quantitative, research designs, particularly experimental and quasi-experimental designs. Make certain that you follow all of the links within the article, and the links and sublinks given in the menu on the left-hand side of the screen.

Trochim, W. K. (2006). Design. Retrieved from the website of the Research Methods Knowledge Base: http://www.socialresearchmethods.net/kb/design.php

Assignment 2

Review Assignment 2 on the course home page, and do whatever you can at this point.

8.4 References

Campbell, L. (2010). Research design: An introduction. Retrieved from: http://www.youtube.com/watch?v=-VoLWmE-vbI

headlessprofessor. (2008). Research designs. Retrieved from http://youtu.be/FpHee7l1cZg

Salkind, N. (2003). Exploring research, 5th ed. Upper Saddle River, NJ: Prentice Hall.

Trochim, W.M.K. (2006). Design. Retrieved from the website of the Research Methods Knowledge Base: http://www.socialresearchmethods.net/kb/design.php

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