1) The average frequency of behavior emitted during a standard unit of time. Formula. Number of responses divided by the number of time units. For example, if 20 responses occur in 5 minutes, the rate is 4 responses per minute.

2) A compound dimensional quantity describing the average number of events per unit of time. Calculated by dividing total count by either total IRT or by the total time during which the responses occurred (i.e., 20 responses in 4 minutes equals 5 responses per minute). Also called frequency.

3) The number of times something occurs within a specified time period. Rates of behavior are often reported in "responses per minute," "responses per hour," or "responses per day."