Free BCABA Experimental Design Practice Questions

The Experimental Design domain represents 7% of the BCABA exam and covers single-case designs, internal validity, threats to interpretation, and replication. Review each answer and explanation as you practice.

The BCABA exam format is 175 questions in 240 minutes; this page is a focused domain sample.

BCABA Experimental Design Sample Questions with Answers

Sample Question 1 — Experimental Design

In a study evaluating a behavior-change procedure, the independent variable is:

  1. A. The participant whose behavior is being studied
  2. B. The condition that is systematically manipulated (Correct answer)
  3. C. The target behavior that is measured throughout the study
  4. D. An uncontrolled event that happens to occur during the study

Correct answer: B

Explanation: B is correct because the independent variable is the variable the experimenter or practitioner deliberately changes to see its effect on behavior. A is the person involved in the study, not a variable that is manipulated. C describes the dependent variable. D describes a potential confounding variable, not the independent variable.

Sample Question 2 — Experimental Design

A BCaBA measures the number of mands a client emits each session while evaluating a new prompting procedure. The number of mands is the:

  1. A. Dependent variable (Correct answer)
  2. B. Independent variable
  3. C. Control condition
  4. D. Confounding variable

Correct answer: A

Explanation: A is correct because the dependent variable is the behavior that is measured to determine whether it changes as a result of the independent variable. B is the prompting procedure being evaluated, not the measured behavior. C refers to a condition, such as baseline, not the measured behavior. D is an uncontrolled variable that could influence the results, not the behavior being measured.

Sample Question 3 — Experimental Design

A team evaluates whether wearing noise-canceling headphones reduces a client's ear covering in the school cafeteria. In this evaluation, the headphones are the:

  1. A. Dependent variable
  2. B. Independent variable (Correct answer)
  3. C. Confounding variable
  4. D. Social validity measure

Correct answer: B

Explanation: B is correct because the headphones are the condition the team introduces and manipulates to evaluate its effect on ear covering. A is ear covering, the behavior being measured. C would be an uncontrolled factor, such as a change in cafeteria noise, rather than the variable deliberately introduced. D would assess whether goals, procedures, or outcomes are acceptable and important to stakeholders.

Sample Question 4 — Experimental Design

Which statement correctly identifies both variables in a study titled "The Effects of Token Reinforcement on Math Problems Completed"?

  1. A. Token reinforcement is the independent variable, and the student is the dependent variable
  2. B. Both token reinforcement and math problems completed are independent variables
  3. C. Token reinforcement is the independent variable, and math problems completed is the dependent variable (Correct answer)
  4. D. Math problems completed is the independent variable, and token reinforcement is the dependent variable

Correct answer: C

Explanation: C is correct because token reinforcement is the manipulated intervention, and the number of math problems completed is the measured behavior. A is wrong because the dependent variable is the measured behavior, not the participant. B is wrong because math problems completed is the behavior measured to evaluate the intervention. D reverses the variables: the intervention is manipulated, and the behavior is measured.

Sample Question 5 — Experimental Design

A researcher evaluates whether 1-minute or 5-minute time-out durations produce greater decreases in a client's aggression. What is the independent variable?

  1. A. The frequency of aggression
  2. B. The duration of time-out (Correct answer)
  3. C. The teacher who implements time-out
  4. D. The classroom where time-out is used

Correct answer: B

Explanation: B is correct because the duration of time-out is the variable systematically manipulated across conditions. A is the dependent variable measured to evaluate the effect of time-out duration. C is an implementer whose behavior should be held constant, not the manipulated variable. D is part of the setting, which should be held constant rather than manipulated.

Sample Question 6 — Experimental Design

Why should only one independent variable be changed at a time when evaluating an intervention?

  1. A. So that changes in the dependent variable can be attributed to that specific variable (Correct answer)
  2. B. Because the Ethics Code prohibits changing more than one intervention at a time
  3. C. So that the dependent variable will show more variability across sessions
  4. D. Because the dependent variable cannot be measured while multiple variables are changing

Correct answer: A

Explanation: A is correct because changing one variable at a time allows the practitioner to determine which variable is responsible for any change in behavior. B is wrong because the rule reflects experimental logic, not a specific ethics code prohibition. C is wrong because increased variability makes effects harder to evaluate, not easier. D is wrong because behavior can still be measured; the problem is that its changes cannot be attributed to one variable.

Sample Question 7 — Experimental Design

A BCaBA introduces a new reinforcement system in the same week that a client begins a new medication, and the client's problem behavior decreases. Which conclusion is MOST accurate?

  1. A. The reinforcement system is the independent variable, and the medication is the dependent variable
  2. B. The reinforcement system caused the decrease, because the behavior changed after it was introduced
  3. C. The medication caused the decrease, because medications typically act faster than behavioral interventions
  4. D. The decrease cannot be attributed to the reinforcement system, because two variables changed at the same time (Correct answer)

Correct answer: D

Explanation: D is correct because when two potential independent variables change simultaneously, their effects are confounded, and neither can be identified as responsible for the change. A is wrong because the medication is not a measured behavior; it is a second variable that changed. B ignores the medication change that occurred at the same time, which could also explain the decrease. C is an unsupported assumption; the design cannot separate the effects of the two variables.

Sample Question 8 — Experimental Design

Internal validity refers to the extent to which:

  1. A. The results of a study apply to other people, settings, and behaviors
  2. B. Two observers record the same values when measuring the same behavior
  3. C. Stakeholders consider the goals and outcomes of an intervention important
  4. D. Changes in behavior can be attributed to the intervention, not other factors (Correct answer)

Correct answer: D

Explanation: D is correct because internal validity concerns whether the study demonstrates that the independent variable, and not uncontrolled variables, produced the change in behavior. A describes external validity. B describes interobserver agreement, which relates to measurement reliability. C describes social validity.

Sample Question 9 — Experimental Design

A study shows a clear functional relation between an intervention and increased requesting for one young child in a clinic. A reader asks whether the same procedure would work for teenagers in a school setting. The reader is asking about:

  1. A. External validity (Correct answer)
  2. B. Procedural integrity
  3. C. Internal validity
  4. D. Interobserver agreement

Correct answer: A

Explanation: A is correct because external validity concerns whether the findings apply to other participants, settings, and behaviors beyond those studied. B concerns whether the intervention was implemented as designed. C concerns whether the intervention caused the change for the child studied, which the study already showed. D concerns the consistency of measurement between observers.

Sample Question 10 — Experimental Design

Which practice MOST directly strengthens a study's internal validity?

  1. A. Selecting goals that the client's family considers highly important
  2. B. Holding other variables constant and replicating the intervention's effect (Correct answer)
  3. C. Including participants of different ages from several different settings
  4. D. Publishing results in a peer-reviewed journal after the study ends

Correct answer: B

Explanation: B is correct because controlling extraneous variables and replicating the effect of the independent variable increase confidence that it caused the change. A addresses social validity rather than whether the intervention caused the change. C primarily addresses external validity by testing whether findings apply more broadly. D may subject a study to review but does not strengthen its internal validity.

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