Partial interval recording
Partial interval recording scores an interval if the target behavior occurs at any time during that interval, however briefly.
The observation period is divided into equal intervals, often 10 to 30 seconds. If the behavior happens at any point during an interval, even once and for a moment, the interval is scored. The observer does not need to keep watching for that behavior for the rest of that interval, which makes the method easier to use while teaching. Results are reported as the percentage of intervals scored.
Partial interval recording tends to overestimate how much of the session the behavior filled, because a 1-second behavior marks the whole interval. It also tends to underestimate count for high-rate behavior, because five hits in one interval are recorded the same as one hit. Because it errs toward catching any occurrence, it is often used for behaviors the team wants to decrease, such as hitting, scripting or calling out.
Like any interval method, it gives an estimate. A smaller percentage of scored intervals over time suggests the behavior is happening in fewer intervals, but the data do not tell exactly how many times it happened or for how long. The RBT should use the interval length in the plan and score strictly by the definition.
Example and non-example
| Example | In 10-second intervals, an RBT marks an interval whenever a child bangs on the table at any point in it. The child bangs once early in interval 3, so interval 3 is scored. |
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| Non-example | Marking an interval only if the child was on task for the entire 10 seconds is whole interval recording. |
Don't confuse it with
| Whole interval recording | Partial interval scores any occurrence in the interval and tends to overestimate; whole interval requires the behavior throughout the interval and tends to underestimate. |
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| Momentary time sampling | Partial interval looks at the whole interval; momentary time sampling looks only at the instant the interval ends. |
Test yourself
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Question 1An RBT divides a 15-minute observation into 15-second intervals and marks an interval if a child bites their nails at any time during it. Which procedure is this?
Show answer
A: Partial interval recording. Scoring an interval when the behavior occurs at any point during it, even briefly, is partial interval recording.
- B: Whole interval recording would require the nail biting to continue through the entire interval.
- C: Momentary time sampling would look only at the moment each interval ends.
- D: Duration recording would time each episode of nail biting rather than mark intervals.
Task A.2 · 40-hour curriculum section C
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Question 2An RBT is using 10-second partial interval recording for screaming. During one interval the client screams four separate times. How should the RBT record that interval?
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A: Mark it once as an interval with screaming. In partial interval recording an interval is scored once if the behavior occurs at any point in it. Further occurrences in the same interval do not change the score, which is why interval data do not give a count.
- B: Interval procedures record whether the behavior occurred in an interval, not how many times.
- C: Each interval is scored only on what happened during that interval.
- D: Requiring the behavior to fill the whole interval is the rule for whole interval recording, not partial interval recording.
Task A.2 · 40-hour curriculum section C
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Question 3During a 60-second interval, a client hums for 5 seconds in the middle of the interval and is quiet at all other times. How would each procedure score this interval for humming?
Show answer
C: Partial interval would score it; whole interval and momentary time sampling would not. Partial interval recording scores any occurrence in the interval, so it scores this one. Whole interval recording needs the behavior for the entire interval, and momentary time sampling needs it at the moment the interval ends; neither condition was met.
- A: Whole interval recording needs humming throughout all 60 seconds, and partial interval recording would score any occurrence.
- B: The client was quiet at the end of the interval, so momentary time sampling would not score it.
- D: Momentary time sampling looks only at the end of the interval, when the client was quiet.
Task A.2 · 40-hour curriculum section C
Answer every question to see your score.
On the RBT exam
This term belongs to task A.2 Discontinuous measurement in content area A, Data Collection and Graphing, which is 13 of the 75 scored questions.