In Applied Behavior Analysis (ABA), data collection is the backbone of decision-making. While continuous measurement involves recording every instance of a behavior, discontinuous measurement is a practical alternative when time, resources, or setting make full observation difficult.
Discontinuous measurement is the process of observing and recording behavior only during pre-determined time intervals, rather than continuously throughout a session.
Why Use Discontinuous Measurement in ABA?
Discontinuous measurement is a valuable tool in Applied Behavior Analysis (ABA) for several reasons. It offers efficiency, making it ideal for busy therapists or educators who juggle multiple responsibilities. It also reduces the observer's burden, enabling meaningful data collection without requiring constant observation. This approach is particularly feasible in group settings such as classrooms, therapy groups, or home environments where continuous monitoring is not always practical.
When It’s Most Appropriate:
Discontinuous measurement works best for behaviors that occur frequently or last for extended periods of time. It is also well-suited for environments where the observer needs to multitask or in situations where exact counts are less critical, but identifying behavioral trends is essential.
"It can be time-consuming and redundant to use continuous data collection for behaviors that happen very frequently. With careful planning, teachers and RBTs can collect discontinuous data on multiple students while managing the class effectively."
— April Torres, M.Ed., BCBA
Types of Discontinuous Measurement
In Applied Behavior Analysis (ABA), there are three main methods used to measure behaviors: Partial Interval Recording, Whole Interval Recording, and Momentary Time Sampling. Each method has its own rules, advantages, and limitations.
1. Partial Interval Recording (PIR)
Partial Interval Recording checks if a behavior happens at any point during a set amount of time. To use this method, divide the observation into equal time intervals, like 5-minutes. If the behavior happens at any time during that interval, you mark “yes.” If it doesn’t happen, mark “no.” PIR is helpful for seeing if a behavior occurs but doesn’t show how long the behavior lasted or how many times it occurred. It can sometimes make a behavior seem like it happens more often than it actually does, so it works best for frequent or ongoing behaviors, especially ones you want to reduce.
2. Whole Interval Recording (WIR)
Whole Interval Recording measures if a behavior happens for the entire duration of a set time interval. Divide the observation session into equal intervals. Mark “yes” only if the behavior occurs during the whole interval. If the behavior stops, even briefly, mark “no.” WIR is good for measuring behaviors that tend to last longer, like staying seated or reading. However, this method can make it seem like a behavior happens less often than it really does, so it’s best for tracking positive behaviors you want to increase.
3. Momentary Time Sampling (MTS)
Momentary Time Sampling checks if a behavior is happening right at the end of each time interval. Break the observation session into equal intervals. At the end of each interval, look to see if the behavior is happening at that exact moment. If it is, mark “yes.” If not, mark “no.” MTS gives quick snapshots of behavior but might overestimate or underestimate how often it really happens, depending on the timing. This method works well in group settings or when it’s hard to observe continuously. It’s also useful for tracking behaviors that last a long time.
Choosing the Right Method
How to Set Up Discontinuous Measurement
- Write down the behavior you’re measuring in clear, simple terms.
- Pick the method that works best for your goal (PIR, WIR, or MTS).
- Decide how long each interval will be, based on how often the behavior happens or how long the behaviors lasts
- Set an observation time (like 1 hour with 10-minute checks).
- Get your materials ready (data sheets, timers, clickers, or apps).
- Train anyone collecting data so they know exactly what to do.
- Test your setup to make sure it works well.
- Start regular sessions and review the data often.
Tools for Data Collection
You’ll need tools like printable data sheets for PIR, WIR, or MTS, or ABA software like Theralytics for digital tracking. Timers or clickers can also help remind you when to check behavior.
How to Analyze the Data
Make bar graphs or line charts to see patterns in the data. Look for trends like certain times of day or situations where the behavior happens more often. Use this information to adjust your plan, but don’t jump to conclusions, each method of measurement has its limits.
Examples in Real Life
- PIR (Partial Interval Recording): Tracking how often aggression happens in a busy classroom.
- WIR (Whole Interval Recording): Measuring how long someone stays focused, like reading without stopping.
- MTS (Momentary Time Sampling): Checking if a student is on-task every 5 minutes during group work.
- Parents: Watching if a child follows bedtime rules at specific times.
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Making Sure Data Is Reliable (IOA)
To make sure the data is accurate, two people can collect data at the same time and compare their results. They should agree at least 80% of the time before making any big decisions based on the data.
FAQ
What interval length should I use?
Shorter intervals = more accurate data; longer intervals = less effort.
Can I switch methods?
Yes, but document changes to ensure data is interpreted correctly.
Is discontinuous measurement acceptable for insurance?
Sometimes, but always confirm payer requirements.
Key Takeaways
- PIR is best for capturing frequent, short behaviors.
- WIR is best for sustained positive behaviors.
- MTS is best for efficiency in group or multitasking settings.
- Always define behaviors clearly, choose appropriate intervals, and ensure IOA.
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