ABA Discontinuous Measurement: Types, Examples & Strategies.

Accurate data collection is central to Applied Behavior Analysis (ABA). Decisions about assessment, intervention, and progress monitoring depend on reliable behavioral data. While continuous measurement methods provide the most precise information, they are not always practical in real-world settings such as classrooms, group therapy, or high-frequency behavior contexts.

Discontinuous measurement offers a practical alternative. By observing behavior during selected time intervals rather than continuously, ABA professionals can collect meaningful data while balancing time, resources, and clinical demands. To learn more about all measurement methods in ABA, including continuous and discontinuous techniques, see our ABA Measurement Study Guide. Understanding how discontinuous measurement works and its limitations is essential for Registered Behavior Technicians (RBTs) and behavior analysts alike.

What Is ABA Discontinuous Measurement ?

In ABA, discontinuous measurement is a data collection approach in which an observation period is divided into predetermined time intervals. The observer records whether the target behavior occurs during part of the interval, the entire interval, or at a specific moment in time.

This approach is commonly referred to as:

• Interval recording
• Time sampling
  

Unlike continuous measurement, discontinuous methods do not capture every instance of behavior. Instead, they provide an estimate of behavior patterns based on sampled observations.

Discontinuous measurement is most appropriate when:

• Behavior occurs very frequently
• Observation time or staff resources are limited
• Continuous data collection is impractical or disruptive
  

---

Discontinuous vs Continuous Measurement

Continuous measurement involves observing and recording behavior throughout the entire session (e.g., frequency, duration, latency). While more precise, it is not always feasible.

Discontinuous measurement:

• Requires less time and effort
• Is easier to implement in applied settings
• Introduces measurement error (over- or underestimation)

ABA professionals must weigh precision versus practicality when choosing between these methods.

Types of Discontinuous Measurement in ABA

There are three primary types of discontinuous measurement used in ABA practice, with one additional group-based variation.

Whole Interval Recording

Definition

In whole interval recording, the behavior is scored only if it occurs for the entire duration of the interval.

If the behavior stops at any point during the interval, it is not recorded.

Measurement Bias

Whole interval recording tends to underestimate behavior, particularly when behaviors occur intermittently.

When to Use Whole Interval Recording

This method is most appropriate when:

• The goal is to increase a desired behavior
  
• Continuous engagement is clinically relevant
  
• A conservative estimate of improvement is preferred
  

Example

A student is recorded as “on task” only if they remain engaged in their work for the entire 1-minute interval.

Partial Interval Recording

Definition

In partial interval recording, the behavior is scored if it occurs at any point during the interval, even briefly.

Measurement Bias

Partial interval recording tends to overestimate behavior, because a short occurrence counts the same as behavior lasting the entire interval.

When to Use Partial Interval Recording

This method is most appropriate when:

• The goal is to decrease problem behavior
  
• Behavior occurs unpredictably or briefly
  
• A conservative estimate of reduction is needed
  

Example

If a child engages in screaming at any time during a 30-second interval, the behavior is recorded as occurring.

Momentary Time Sampling (MTS)

Definition

Momentary time sampling records whether the behavior is occurring at the exact moment the interval ends.

No observation is required during the rest of the interval.

Measurement Bias

MTS may either under- or overestimate behavior depending on timing, but often misses behavior that occurs outside the sampling moment.

When to Use Momentary Time Sampling

MTS is useful when:

• Observation time is extremely limited
  
• Multiple individuals must be monitored
  
• Approximate estimates are acceptable
  

Example

At the end of a 5-minute interval, the observer checks whether the student is on task at that moment only.

Planned Activity Check (PLACHECK)

Definition

A Planned Activity Check (PLACHECK) is a variation of momentary time sampling used to measure group behavior.

Instead of scoring one individual, the observer records how many individuals in a group are engaged in the target behavior at the sampling moment.

When to Use PLACHECK

PLACHECK is appropriate when:

• Monitoring classroom or group engagement
  
• Individual-level precision is not required
  
• Time and staffing resources are limited
  

Example

At the end of a 10-minute interval, a teacher records how many students are actively participating in group work.

Advantages of Discontinuous Measurement

Discontinuous measurement offers several practical benefits:

• Requires less time than continuous methods
  
• Easier to implement in classrooms and group settings
  
• Suitable for high-frequency or long-duration behaviors
  
• Allows observers to manage multiple responsibilities
  
• Widely used in applied ABA practice
  

Limitations and Accuracy Considerations

Despite its practicality, discontinuous measurement has important limitations:

• Does not capture all instances of behavior
  
• Introduces systematic bias (over- or underestimation)
  
• Accuracy depends heavily on interval length
  
• Less appropriate for low-frequency behaviors
  

Shorter intervals generally improve accuracy but increase observer workload. ABA professionals must select interval lengths carefully based on behavioral goals and context.

For a complete overview of all ABA measurement methods and strategies, refer to our RBT Complete Study Guide

Choosing the Right Discontinuous Measurement Method

The choice of method should align with the clinical goal:

• Increase behavior → Whole interval recording
  
• Decrease behavior → Partial interval recording
  
• Limited time/resources → Momentary time sampling
  
• Group monitoring → PLACHECK
  

The selected method should also consider:

• Behavior characteristics
  
• Setting constraints
  
• Observer training and consistency
  

Practical Examples in ABA Settings

Discontinuous measurement is commonly used to track:

• On-task behavior in classrooms
  
• Stereotypy or self-stimulatory behavior
  
• Disruptive or aggressive behavior
  
• Social engagement during group activities
  
• Independent work completion
  

These methods allow meaningful data collection even when continuous observation is unrealistic.

RBT Exam Considerations

For the RBT exam, candidates should remember:

• Partial interval recording overestimates behavior
  
• Whole interval recording underestimates behavior
  
• Momentary time sampling records behavior at one specific moment
  
• Discontinuous measurement does not record every instance
  
• Continuous methods are preferred when precision is required
  

Understanding these distinctions is critical for answering exam questions accurately.

Summary

Discontinuous measurement is a core ABA data collection strategy that balances practicality with clinical usefulness. While it does not provide the precision of continuous measurement, it allows RBTs and ABA professionals to collect meaningful behavioral data in real-world environments.

By understanding the strengths, limitations, and appropriate applications of each discontinuous method, practitioners can make informed, ethical, and data-driven decisions to support effective intervention planning.

Frequently Asked Questions About Discontinuous Measurement in ABA