ABA glossary
Duration
Definition
How long a behavior lasts, from onset to offset. It can be reported as total duration per session or as mean duration per occurrence.
In plain words
Duration is the right measure when how long a behavior lasts matters more than how often it happens, such as tantrums, time on task, or time spent in the bathroom. Total duration (the sum of all episodes) shows how much of the session the behavior took up; mean duration (total divided by the number of episodes) shows how long a typical episode lasted. Accurate duration recording needs clear onset and offset rules in the operational definition, so that observers start and stop the timer at the same moments.
Example from a session
During a 1-hour session, Bella has three tantrums lasting 2, 5, and 8 minutes. The RBT starts a stopwatch when Bella begins crying and screaming and stops timing at the last cry or scream once 30 seconds pass with neither, as the definition says. She records a total duration of 15 minutes and a mean duration of 5 minutes per tantrum, which the BCBA graphs as total duration per session.
For BCBA candidates and supervisors
Duration data are sensitive to how onset and offset are defined, so analysts check IOA with total duration IOA (shorter total divided by longer total) or, more stringently, mean duration-per-occurrence IOA. When continuous duration recording is impractical, analysts may use whole-interval recording or momentary time sampling as estimates, knowing the bias each introduces. For goals to increase engagement, duration often reflects progress better than counts of "on-task" episodes.
Often confused with latency, interresponse time
Duration is how long the behavior itself lasts. Latency is the time before the behavior starts, measured from a cue. IRT is the time between two responses. If the stopwatch runs while the behavior is happening, it is duration; if it runs before the behavior starts, it is latency or IRT.
Exam tip
For mean duration, divide total duration by the number of episodes, not by session length. Three episodes totaling 12 minutes have a mean duration of 4 minutes, whatever the session length.
Can you spot duration in a scenario?
Practice RBT A.1 with exam-style questions and instant feedback.