Variable (1 of 2)

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A variable is any measured characteristic or attribute that differs for different subjects. For example, if the weight of 30 subjects were measured, then weight would be a variable.

Quantitative and Qualitative
Variables can be quantitative or qualitative. (Qualitative variables are sometimes called "categorical variables.") Quantitative variables are measured on an ordinal, interval, or ratio scale; qualitative variables are measured on a nominal scale. If five-year old subjects were asked to name their favorite color, then the variable would be qualitative. If the time it took them to respond were measured, then the variable would be quantitative.

Independent and Dependent
When an experiment is conducted, some variables are manipulated by the experimenter and others are measured from the subjects. The former variables are called "independent variables" or "factors" whereas the latter are called "dependent variables" or "dependent measures."