Operational definitions provide meanings that are limited to the scope of the research being described. For example, we might induce frustration by blocking an organism for 15 minutes from a desired goal. Such definitions aid in communicating our ideas to other scientists. They may make results less interesting to nonscientists, but they also make it possible for another psychologist to repeat a study, with large or small variations, to see if its results are stable. Nominal Scales Having determined an operational definition of variables, the next objective is to measure them accurately.
All subjects belong to one or the other group.
When the sex variable is measured on a nominal scale, subjects are divided into two categories or groups according to gender. The numbers used to identify football players also form a nominal scale. There is no order, or sequence, or quality, implied by such a designation. Player number 60 is not twice as good or twice as large as player number 30. An ordinal scale permits a variable to be identified in some sort of sequence, or ranking.