Identifies one or more specific, observable events or conditions such that any other researcher can independently measure and/or test for them.
Example: A researcher measuring happiness and depression in college students decides to use a ten-question happiness scale to measure positive outlook in her subjects. In other words, her operational definition of happiness in this case is a given subject’s score on the test.
Grinnell, R. (2009). Operational Definition. Psych Central. Retrieved on April 26, 2015, from http://psychcentral.com/encyclopedia/2009/operational-definition/