BCBA Measurement & Data Practice Questions
Measurement, Data Display, and Interpretation tests whether you can choose the right measure, calculate it correctly, and read a graph the way a behavior analyst does. Expect calculations (rate, IOA) and visual-analysis questions.
What Domain C covers
The 6th Edition Test Content Outline lists 12 tasks in this domain. Baseline has practice questions mapped to every one of them.
- C.1Writing operational definitions
- C.2Direct, indirect, and product measures
- C.3Measuring occurrence (count, frequency, rate, percentage)
- C.4Temporal measures: duration, latency, interresponse time
- C.5Continuous vs. discontinuous measurement
- C.6Interval recording and time sampling
- C.7Efficiency measures: trials to criterion, cost-benefit, training duration
- C.8Validity and reliability of measurement (including IOA)
- C.9Choosing a measure that fits the behavior and setting
- C.10Graphing data: line graphs, bar graphs, cumulative records
- C.11Interpreting graphed data (visual analysis)
- C.12Measuring procedural integrity
What to master
- Writing operational definitions that two observers would agree on.
- Choosing between count, rate, duration, latency, and interresponse time based on the behavior's critical dimension.
- Discontinuous methods — partial-interval, whole-interval, momentary time sampling — and how each one biases the estimate.
- Interobserver agreement methods and the difference between accuracy, reliability, and validity.
- Visual analysis: level, trend, variability, immediacy of effect, and overlap.
Common traps
- Remembering which interval method over- or underestimates: partial-interval overestimates, whole-interval underestimates.
- Comparing raw counts from sessions of different lengths instead of converting to rate.
- Assuming reliable data are accurate — consistent observers can be consistently wrong.
Free Measurement & Data practice questions
Try these original questions written to match the format of the BCBA exam.
1. Compared with what actually occurred, partial-interval recording tends to:
- Provide an exact count of responses
- Overestimate the proportion of the session in which the behavior occurred
- Underestimate the proportion of the session in which the behavior occurred
- Produce the same estimate as whole-interval recording
Show answer and explanation
Answer: B. Overestimate the proportion of the session in which the behavior occurred
An interval is scored if the behavior occurs at any point during it, so brief occurrences make whole intervals count — partial-interval recording overestimates occurrence (and can underestimate the count of high-rate behavior). Whole-interval recording tends to underestimate.
2. During a 30-minute session, Observer A records 8 instances of calling out and Observer B records 10. What is the total count interobserver agreement (IOA)?
- 80%
- 125%
- 20%
- 90%
Show answer and explanation
Answer: A. 80%
Total count IOA = smaller count ÷ larger count × 100 = 8 ÷ 10 × 100 = 80%. It is a simple measure but cannot show whether the two observers recorded the same instances.
Practice all 60 Measurement & Data questions
Full Prep includes every question in this domain with explanations, smart practice that targets your weakest tasks, unlimited timed mock exams, and an AI tutor. Start with the free diagnostic to see where you stand.