Percentage calculator for ABA data
Percentage is the part divided by the total, times 100. In ABA it's used for correct trials, independent steps in a task analysis, and intervals in interval recording.
How to calculate a percentage
Percentage = part ÷ total × 100.
- Correct trials: 8 correct responses out of 10 trials is 80% correct.
- Task analysis: a client completes 6 of 8 handwashing steps independently: 6 ÷ 8 × 100 = 75% of steps independent.
- Intervals: the behavior is scored in 9 of 30 intervals: 9 ÷ 30 × 100 = 30% of intervals.
Common mistakes
- Using the wrong total, such as the number of correct answers plus prompted ones when the total should be every trial presented.
- Reading a percentage of intervals as a percentage of time. Partial interval recording tends to overestimate and whole interval recording to underestimate how much of the time the behavior happened; the interval recording calculator shows the difference.
- Comparing percentages built on very different totals: 1 of 2 and 50 of 100 are both 50%, but say very different things about a skill.
Practice problems
| Problem | Answer |
|---|---|
| A client answers 14 of 20 trials correctly, 3 of them after a prompt. What percentage was correct and independent? | 11 independent correct of 20 = 55% independent; 14 of 20 = 70% correct including prompted trials. Score as the plan defines it. |
| A toothbrushing task analysis has 12 steps; the client does 9 without help. Percentage of steps independent? | 9 ÷ 12 × 100 = 75%. |
| In 40 ten-second intervals, on-task behavior lasts the whole interval in 26. Whole interval percentage? | 26 ÷ 40 × 100 = 65% of intervals. |
| Monday: 8 of 10 correct. Tuesday: 16 of 20 correct. Which day was better? | Neither: both are 80%. |
On the RBT exam
This calculator practises task A.6 Calculating and summarizing data. On the exam you get a dry-erase board but no calculator, so once you've checked a few answers here, practise doing them by hand.