BCBA Plan

Measurement, Data Display, and Interpretation

12% of the BCBA exam · blueprint Test Content Outline 6th ed. (since 2025)

Short answer

Domain C is 21 of 175 scored questions (12%). It covers selecting a measurement procedure that matches the dimension of behavior targeted, continuous measures (count, rate, duration, latency, interresponse time) versus discontinuous time sampling, the accuracy, reliability and validity of measurement, interobserver agreement methods, equal-interval graphing conventions, and visual analysis of level, trend, variability, immediacy and overlap.

Why it matters on this exam

Every intervention question eventually asks whether the data justify the decision. Domain C is how you read that.

Key concepts

Common mistakes

Worked example

Baseline is variable with an upward trend; intervention shows a higher level but the same upward trend. The trend continuing through the phase change weakens the claim of experimental control. That is an interpretation problem, not a data-collection problem.

Original practice questions

Measurement, Data Display, and InterpretationDifficulty 3/5

Two observers record a low-rate behavior using 10-second intervals. Most intervals contain no occurrence and interval-by-interval agreement is 96%. What is the concern?

  1. AAgreement is too high to be credible, so both observers should be retrained
  2. BInterval-by-interval IOA inflates when most intervals are empty; unscored-interval IOA is the appropriate check
  3. CThe observers should switch to partial-interval recording to raise sensitivity
  4. DAgreement cannot be computed for low-rate behavior without a longer observation window
Show answer and rationale

Correct: B. With mostly empty intervals, agreements on non-occurrence dominate and inflate interval-by-interval IOA. Scored-interval (for high-rate) and unscored-interval (for low-rate) IOA correct for this by only counting the intervals that matter.

  • A — High agreement is not itself a reason to discard data; the metric is the problem.
  • C — The recording method is not the issue; the agreement calculation is.
  • D — Agreement can be computed; it simply needs a method suited to the rate.
Measurement, Data Display, and InterpretationDifficulty 3/5

Baseline shows a clear increasing trend in the therapeutic direction. Intervention is introduced and the behavior continues to increase at the same rate. What is the most defensible interpretation?

  1. AInterobserver agreement must be low, because a real effect would show a level change
  2. BThe intervention produced a strong effect, shown by continued improvement in the therapeutic direction
  3. CThe data do not demonstrate experimental control because the baseline trend already predicted this outcome
  4. DThe intervention should be intensified immediately to accelerate the existing trend
Show answer and rationale

Correct: C. A baseline trending in the therapeutic direction predicts continued improvement without treatment. When the intervention phase merely continues that trend, level and trend changes cannot be attributed to the intervention.

  • B — An unchanged trend is not evidence of an effect.
  • D — Intensifying before establishing control compounds the interpretation problem.
  • A — Nothing in the scenario speaks to measurement agreement.
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Related areas: Behaviorism and Philosophical Foundations · Concepts and Principles · Experimental Design · Ethical and Professional Issues

Primary references

  1. BCBA Test Content Outline (6th ed.), in effect since 2025 — Behavior Analyst Certification Board (BACB) · primary · retrieved 2026-09-22, verified 2026-09-22
Last reviewed: 2026-10-18Next review by: 2026-12-17Reviewed by: Openverse editorial team, Authoring and fact verificationHow we verify facts