A.2 Discontinuous Measurement

By RBThub

Imagine you are a teacher in a classroom with 30 students. Can you watch every single student for every single second of the day? Impossible, right?

This is where Discontinuous Measurement saves the day. Unlike Continuous Measurement (where we watch everything), Discontinuous Measurement allows us to take "samples" or "snapshots" of behavior. It's less accurate, but much more practical for busy environments.

Executive Summary

This video provides an in-depth overview of Discontinuous Measurement in ABA, contrasting it with continuous measurement. It focuses on Partial Interval, Whole Interval, and Momentary Time Sampling. The objective is to help RBTs understand when to use these methods effectively, especially when resources or observation time is limited.

⏱️ Video Timeline

00:00

Introduction
Introduces discontinuous measurement as a complementary method to continuous measurement, used when full-session continuous observation is not feasible.

00:40

Partial Interval Recording
Defines partial interval recording: if behavior happens at any time during the interval, it counts. Discusses its tendency to overestimate behavior.
Best for: Behaviors you want to DECREASE.

02:28

Whole Interval Recording
Behavior must occur throughout the entire interval. Highlights its tendency to underestimate behavior.
Best for: Behaviors you want to INCREASE (like studying or sitting).

04:20

Momentary Time Sampling (MTS)
Observer records behavior only at the exact end of the interval. Allows for multitasking.
Risk: Data can be skewed if learners "time" their behavior.

06:13

Planned Activity Check (PLACHECK)
A group version of MTS. The teacher looks up at the end of the interval and counts how many students are engaged.

🔑 Key Insights

Partial Interval overestimates behavior. Use it to reduce bad habits.

Whole Interval underestimates behavior. Use it to build good habits (endurance).

MTS is the easiest for teachers because you don't have to watch the whole time.

PLACHECK is "Momentary Time Sampling for Groups."

❓ Frequently Asked Questions

Q: Which method is best for decreasing problem behavior?

A: Partial Interval Recording. Because it overestimates, it catches even small instances of the problem behavior, making sure we don't miss it.

Q: What is the main limitation of Whole Interval Recording?

A: It tends to underestimate. If a child studies for 59 seconds of a 1-minute interval and looks away for 1 second, it counts as a "fail" (non-occurrence).

1. Partial Interval Recording

The Official Definition: A time sampling method where the observer records whether the behavior occurred at any time during the interval.

The "Human" Translation: Divide your time into small blocks (e.g., 10 minutes into 1-minute blocks). If the behavior happens even once—for a split second—you check the box "YES."

Clinical Example

You are tracking "swearing." The interval is 5 minutes. The client swears once at minute 2. You mark the interval as "Occurred." Even if they don't swear again for the rest of the 5 minutes, the box is checked.

Watch Out!

Overestimation Risk: Because one tiny instance counts for the whole block, this method makes it look like the behavior happens more than it actually does.

2. Whole Interval Recording

The Official Definition: A time sampling method where the behavior is recorded only if it occurs throughout the entire interval.

The "Human" Translation: This is the "All or Nothing" method. If the interval is 1 minute, the client must do the behavior for 60 seconds straight. If they stop for even one second, it doesn't count.

Clinical Example

You want a child to sit in their seat. Interval = 2 minutes. They sit perfectly for 1 minute and 50 seconds, but stand up for the last 10 seconds. You mark "Did Not Occur."

3. Momentary Time Sampling (MTS)

The Official Definition: A time sampling method where the presence of the behavior is recorded only at the precise moment the interval ends.

The "Human" Translation: The "Glance Up" method. You set a timer for 5 minutes. You do your work. When the timer beeps, you look up. Is the client working? Yes/No. Then you restart the timer. You ignore everything that happened in between the beeps.

Clinical Example

A teacher is busy grading papers. Every 10 minutes, she looks up to see if Johnny is on task. If he is, she marks "Yes." If he is playing, she marks "No."

📝 Knowledge Check

Can you beat the exam traps? Try these questions.

Q1: An RBT is tracking "hand flapping." If the behavior happens for 1 second during a 30-second interval, the RBT marks it as an occurrence. Which method is this?

Answer: Partial Interval Recording.
Because it was recorded "at any time" during the interval.

Q2: You want to INCREASE a student's reading stamina. Which measurement method is best?

Answer: Whole Interval Recording.
We use Whole Interval for behaviors we want to increase (duration/stamina) because it is stricter.

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