ABA glossary
Frequency
Also called count
Definition
The number of times a behavior occurs during an observation, also called a count. Some textbooks use "frequency" to mean rate (count per unit of time), so check how a question uses the word.
In plain words
Counting each occurrence is the most basic continuous measure and works best for behaviors with a clear start and end, such as hits, requests, or bites. A count is only meaningful alongside the observation time: 10 hits in 10 minutes and 10 hits in a full day are very different. When session lengths vary, teams convert counts to rate. Counting is a poor fit for behaviors that last a long and varying time (such as crying episodes) or that happen so fast they blur together.
Example from a session
The plan asks the RBT to tally every mand during a 60-minute session. Each time Eli asks for something using words or a picture card, the RBT makes a tally mark: 14 by the end. She writes "14 mands, 60-minute session" so the BCBA can compare sessions of different lengths. If she had written only "14," the number could not be compared with a 30-minute session later in the week.
For BCBA candidates and supervisors
The field uses "frequency" in two ways: as a raw count (common in RBT training materials) and as a synonym for rate (common in some textbooks and in precision teaching). Analysts make the meaning explicit in their data systems and reports. Count is appropriate only when the observation period is constant across sessions; otherwise report rate. For discrete trials, where the number of opportunities is controlled by the teacher, percentage correct or trials to criterion is usually more informative than a count.
Often confused with rate, duration
A count says how many times; a rate says how many times per unit of time; duration says how long. If a stem gives a number of occurrences and a session length and asks for a comparison across sessions of different lengths, it wants rate, not count. If the behavior lasts a varying amount of time, duration usually fits better.
Exam tip
Check the stem for a time unit. "Hit 7 times" is a count. "Hit 7 times in 35 minutes, compare with yesterday's 60-minute session" calls for rate. If an option uses "frequency," read the surrounding words to see whether it means count or rate.
Can you spot frequency in a scenario?
Practice RBT A.1 with exam-style questions and instant feedback.