When collecting behavioral data, selecting the right measurement procedure is crucial. While continuous measurement provides the most precise data by capturing every instance of a behavior, it is not always practical. In many cases, discontinuous measurement procedures offer a more feasible way to track behavior while still providing valuable insights.
What Are Discontinuous Measurement Procedures?
Discontinuous measurement involves taking samples of behavior rather than recording every occurrence. These methods are useful when:
- Observing behavior continuously is too time-consuming or impractical.
- The setting makes constant observation difficult.
- Approximate data is sufficient for making treatment decisions.
These methods divide the observation period into intervals of a specific length (e.g., 10 seconds, 30 seconds, or 1 minute). The observer then records behavior based on whether it occurs at any point, throughout the entire interval, or at a specific moment—depending on the chosen procedure.
Types of Discontinuous Measurement Procedures
- Partial Interval Recording
- Whole Interval Recording
- Momentary Time Sampling (MTS)
Let’s take a closer look at each.
Partial Interval Recording
How It Works
Partial interval recording involves breaking an observation period into small intervals and recording whether the behavior occurs at any point during each interval. If the behavior happens at least once, the interval is marked with a “+” (yes). If it does not occur at all, it is marked with a “-” (no).
Pros & Cons
✔ Useful for tracking behavior over time
✔ Ideal for behaviors that occur frequently
✖ Overestimates behavior – it marks the interval “+” even if the behavior occurs just once for a brief moment.
Common Uses
- Measuring stereotypic behaviors (e.g., hand flapping, rocking)
- Tracking self-injurious behaviors
- Monitoring disruptive behaviors in a classroom
Whole Interval Recording
How It Works
With whole interval recording, the behavior must occur for the entire duration of the interval to be recorded as a “+”. If the behavior stops at any point, it is marked with a “-”.
Pros & Cons
✔ Useful for behaviors that should be maintained for extended periods
✔ Encourages continuous engagement
✖ Underestimates behavior – a behavior that occurs frequently but not continuously might not be recorded accurately.
Common Uses
- Measuring on-task behavior in a classroom
- Tracking cooperative play
- Assessing sustained attention in work settings
Momentary Time Sampling (MTS)
How It Works
Momentary Time Sampling is a method where behavior is recorded only at the end of an interval. If the behavior is occurring at that precise moment, the interval is marked “+”; if not, it is marked “-”.
Pros & Cons
✔ Less time-intensive – does not require constant observation
✔ Ideal for large groups
✖ May miss behaviors – only captures snapshots of behavior, leading to potential underestimation.
Common Uses
- Measuring social engagement in a group setting
- Observing task engagement in a work or school environment
- Evaluating compliance with rules or instructions
Choosing the Right Measurement Procedure
Each of these discontinuous measurement methods serves a different purpose. Here’s a quick guide:
| Method | Best For | Key Consideration |
|---|---|---|
| Partial Interval Recording | High-frequency behaviors (e.g., nail biting, rocking) | Overestimates behavior |
| Whole Interval Recording | Sustained behaviors (e.g., staying on-task) | Underestimates behavior |
| Momentary Time Sampling | Large groups, classroom settings | May miss brief behaviors |
While discontinuous measurement may not provide as much precision as continuous measurement, it is often the most practical choice in real-world settings. Selecting the right procedure depends on the behavior being tracked, the environment, and the goals of the intervention.
Final Thoughts
Discontinuous measurement procedures play a vital role in behavioral assessment. While they have limitations, they are valuable tools when continuous data collection isn’t feasible. By choosing the right method—whether Partial Interval, Whole Interval, or Momentary Time Sampling—behavior analysts and educators can gather meaningful data to guide interventions and support individuals effectively.