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How to Design and Evaluate Research in Education Book Cover
How to Design and Evaluate Research in Education, 5/e
Jack R. Fraenkel, San Francisco State University
Norman E. Wallen, San Francisco State University

Variables and Hypotheses


Categorical variable   Data (variables) that differ only in kind, not in amount or degree.
Constant   A characteristic that has the same value for all individuals.
Dependent variable   A variable affected or expected to be affected by the independent variable; also called "criterion" or "outcome variable."
Directional hypothesis   A relational hypothesis stated in such a manner that a direction, often indicated by "greater than" or "less than," is hypothesized for the results.
Experimental variable   The variable that is manipulated (systematically altered) in an intervention study by the researcher.
Extraneous variable   A variable that makes possible an alternative explanation of results; an uncontrolled variable.
Hypothesis   A tentative, testable assertion regarding the occurrence of certain behaviors, phenomena, or events; a prediction of study outcomes.
Independent variable   A variable that affects (or is presumed to affect) the dependent variable under study and is included in the research design so that its effect can be determined; sometimes called the "experimental" or "treatment" variable.
Manipulated variable   See experimental variable.
Nondirectional hypothesis   A prediction that a relationship exists without specifying its exact nature.
Outcome variable   See dependent variable.
Quantitative variable   A variable that is conceptualized and analyzed as distinct categories, with no continuum implied.
Relationship   A connection between two qualities or characteristics (e.g., motivation and learning).
Treatment variable   see experimental variable.
Variable   A characteristic that can assume any one of several values, for example, cognitive ability, height, aptitude, teaching method.