GoalTallyQuick answer: In whole interval recording you mark an interval only if the behavior occurred continuously for the entire interval, and report the percentage of intervals scored. Because a brief pause means the interval isn't scored, whole interval recording tends to underestimate how much of the time the behavior happened. That makes it a conservative measure for behaviors you want to increase.
When to choose whole interval recording
- Behaviors that should last: on-task, engaged, in seat, cooperative play.
- The goal is to increase the behavior, so underestimating won't overstate progress.
- You can watch the student continuously for each interval. If you can't, consider momentary time sampling.
How to record
- Define the behavior and what breaks it, for example: on-task means eyes on the work or the teacher; looking away for more than 2 seconds ends it.
- Choose the interval and observation length, such as 15-second intervals for 15 minutes (60 intervals).
- Watch each whole interval. Mark the box only if the behavior lasted the entire interval; leave it blank at the first break.
- Count and divide: marked intervals ÷ intervals observed × 100.
- Graph % of intervals for each observation, or score on screen with the interval timer.
Worked example
On-task behavior was observed for 15 minutes with 15-second intervals (60 intervals). The student was on task for the whole of 39 intervals: 39 ÷ 60 × 100 = 65% of intervals. The true share of time on task was probably a little higher, because intervals with a short break weren't counted.
Making whole interval data more accurate
- Use short intervals, often 5 to 15 seconds. Longer intervals make the underestimate worse.
- Write down what counts as a break in the behavior, so every observer ends an interval at the same point.
- Keep the interval length the same from session to session.
- Check agreement with a second observer now and then: agreeing intervals ÷ total intervals × 100.
For behaviors you want to reduce, partial interval recording is the more common choice.
Frequently asked questions
What's the difference between whole and partial interval recording?
Whole interval scores an interval only if the behavior lasted all of it; partial interval scores it if the behavior happened at any point. Whole interval tends to underestimate and partial interval tends to overestimate.
Why does whole interval recording underestimate?
A behavior that fills 9 seconds of a 10-second interval still leaves the interval unscored, so time spent in the behavior goes uncounted.
What interval length should I use?
Short intervals, commonly 5 to 15 seconds, give a closer estimate. Pick one you can score reliably and keep it the same every time.
Can I track on-task and off-task together?
Yes. Add up to three behaviors; each box shows a letter per behavior to circle, with a separate percentage for each.
More free graphs and data sheets
Last updated · Written by the MiniTools team.