Continuous Measurement – Frequency, Rate, Duration, IRT, Latency

Continuous Measurement on the RBT Exam

The first thing you should study and learn for the RBT exam is continuous measurement. Not only does it appear first on the task list, but it’s straightforward and easy to grasp. You will be using continuous measurement more than any other measurement in applied behavior analysis practice. A registered behavior technician should know the following continuous measurement terms: frequency, rate, duration, IRT (interresponse time), and latency. Continuous measurement in applied behavior analysis measures every instance of behavior during a class, session, or day. You will primarily use continuous measurement working as an RBT in the field of ABA. Discontinuous measurement is typically reserved for situations where you are low on resources, time, or are taking data on multiple students at once. Let’s look at the most basic type of continuous measurement first: frequency.


Frequency is a count. It isn’t any more complicated or difficult than that. When you are taking frequency data, all you are doing is counting how many times something happens. If I want frequency data on how many times your client elopes then all you do is count how many times your client elopes. If I want frequency on the number of cookies you ate, or the number of beers you drank, or the number of text messages you sent all I would do is count how many times that behavior happened. Frequency is not complicated. More often than not you’ll see rate used in place of frequency, so let’s talk about rate next.


Rate is frequency with a time component. Rate is frequency divided by time. Rate is frequency/time. Rate is frequency per time. No matter how you want to remember it, rate is directly related to frequency. The only difference is you add in a time component. If I count 6 beers drank that is frequency. In order to make it rate, I would add a time component. I drank 2 beers peer hour. If you wanted to make your elopement frequency into rate, you would just add time. Your client eloped 3 times per hour, or 3 times per day. You typically want to use time and not “sessions.” Session time can vary, time is more concrete. Speaking of time, let’s look at duration next.


Duration is exactly what it sounds like – how long something occurs. When you take duration data you are measuring how long a behavior occurs. If you want to take duration data on how long it takes a client to eat all you would need is a timer. You start the timer when the client starts eating, and you stop it when the client is done eating. That is your duration. Other than frequency, duration is the easiest type of measurement to understand and implement. The next two measurements, IRT and latency, give people the most difficulty.


Latency is the time between the presentation of the SD and the start of a response. It’s the time between the instruction and the start of a response. For instance, your alarm goes off and it takes you 5 minutes to start getting out of bed. The latency is five minutes. Your mom asks you to take out the trash. It takes you 10 minutes to start taking out the trash. The latency is 10 minutes. You tell your client to pick up their toys. It takes them 20 seconds to start picking up their toys. The latency is 20 seconds. IRT is directly related to latency.

IRT (Interresponse Time)

IRT, or interresponse time, is the time in between two responses. More importantly, two response in the same response class. If your client takes 20 seconds in between bites of food, the IRT is 20 seconds. If you go 5 hours in between meals, the IRT is 5 hours. Interresponse time is confusing at first, but once you understand that its just the time in between two responses, it becomes very simple.

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