Hypothesis and Variables
A variable is a trait or characteristic with two or more categories. A category (or level) is simply an aspect of a variable. For example, if the variable is “gender,” the categories would be male and female. Categories must be exhaustive and mutually exclusive—all participants should fall into one and only one category. A variable should be defined operationally—meaning that it should be defined clearly and specifically such that it can be replicated by another researcher.
The independent variable is the input or stimulus. It is what the tester manipulates. In an experimental design, the variable is physically manipulated. In a non-experimental design, it is observed.
The dependent variable is the output or response.
A research hypothesis indicates that there is an expected relationship between the independent and dependent variable. Its wording implies whether the study will be experimental or non-experimental in nature. Directional hypotheses predict that one group will have a higher or lower result than another group. Non-directional hypotheses predict a difference between the groups but not in which direction.
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References:
Leedy, Paul D. & Ormrod, Jeanne Ellis. (2001). Practical research: Planning and design (7th ed.). Columbus: Merrill Prentice Hall.
Patten, Mildred L. (2002). Understanding research methods: An Overview of the essentials (3rd ed.). Los Angeles: Pyrczak Publishing.
Schutt, Russell K. (1999). Investigating the social world: the Process and practice of research (2nd ed.). Thousand Oaks: Pine Forge Press.
Solso, Robert L., Johnson, Homer H., & Beal, M. Kimberly. (1998). Experimental psychology: a case approach (6th ed.). New York: Longman.
