BCBA - Board Certified Behavior Analyst Experimental Design Questions and Answers — Questions and Answers
Question 1: A behavior analyst is working with a student to increase the time they spend engaged in on-task behavior. The analyst decides to use an experimental design where the criterion for reinforcement is systematically increased as the student demonstrates stable performance at each level. For example, the student first earns reinforcement for 5 minutes of on-task behavior, then 10 minutes, then 15 minutes. Which experimental design is the analyst using?
- Multiple baseline design
- Reversal (A-B-A-B) design
- Changing criterion design (Correct answer)
- Alternating treatments design
Correct answer: Changing criterion design
The changing criterion design is the correct answer because it involves evaluating the effect of an intervention by systematically and incrementally changing the criterion for reinforcement in a step-wise fashion. Experimental control is demonstrated when the participant's behavior closely tracks the changes in the criterion.
Question 2: A BCBA is designing a study to evaluate the effectiveness of an intervention. A potential threat to internal validity is 'history.' Which of the following scenarios BEST illustrates this threat?
- The participant becomes more familiar with the testing procedures over time, leading to improved performance.
- The observers collecting data subtly change their definition of the target behavior over the course of the study.
- While the intervention is being implemented at school, the participant's parents begin a new, similar behavior plan at home. (Correct answer)
- The participant shows improvement in social skills, which may be due to their natural cognitive and emotional development.
Correct answer: While the intervention is being implemented at school, the participant's parents begin a new, similar behavior plan at home.
History, as a threat to internal validity, refers to any external event that occurs during the course of an experiment that is not part of the manipulation and could be responsible for the results. The implementation of a similar behavior plan at home is an outside event that could confound the effects of the school-based intervention.
Question 3: Which of the following is a primary advantage of using a multiple baseline design over a reversal (A-B-A-B) design?
- It provides a more powerful demonstration of experimental control.
- It is more effective for comparing the effects of two or more different interventions.
- It does not require the withdrawal of an effective intervention. (Correct answer)
- It is the only design that allows for the analysis of prediction, verification, and replication.
Correct answer: It does not require the withdrawal of an effective intervention.
A key advantage of the multiple baseline design is that it does not require withdrawing the intervention once it has been implemented. This is particularly important from an ethical standpoint when dealing with severe challenging behaviors (e.g., self-injury) or when it is undesirable to reverse newly acquired skills.
Question 4: In single-case experimental designs, the core components of baseline logic are prediction, verification, and replication. Verification is demonstrated when:
- the intervention is implemented again, and the data pattern from the first intervention phase is reproduced.
- the baseline level of responding is projected to continue if the independent variable is not introduced.
- the independent variable is withdrawn, and responding returns to a level that is consistent with the original baseline. (Correct answer)
- the effects of the independent variable are shown across multiple different behaviors, settings, or subjects.
Correct answer: the independent variable is withdrawn, and responding returns to a level that is consistent with the original baseline.
Verification involves demonstrating that the baseline level of responding would have likely remained the same had the independent variable not been introduced. In a reversal design, this is accomplished by withdrawing the intervention and observing a return to baseline levels, thus verifying the initial prediction.
Question 5: A behavior analyst wants to quickly compare the effectiveness of two different function-based interventions for reducing a student's off-task behavior: differential reinforcement of alternative behavior (DRA) and noncontingent reinforcement (NCR). Which experimental design would be the most efficient for this purpose?
- Reversal (A-B-A-B) design
- Alternating treatments design (Correct answer)
- Changing criterion design
- Multiple baseline across behaviors design
Correct answer: Alternating treatments design
The alternating treatments design (also known as a multielement design) is the most appropriate choice for directly and efficiently comparing the effects of two or more distinct interventions. It involves the rapid and random alternation of the conditions, allowing for a clear comparison within a short period.
Question 6: All of the following are defining features of single-case experimental designs EXCEPT:
- the use of large, randomized control groups. (Correct answer)
- the participant serves as their own control.
- repeated measures are taken over time.
- experimental control is demonstrated through replication within the design.
Correct answer: the use of large, randomized control groups.
Single-case designs are characterized by the individual participant serving as their own control, the use of repeated measures to establish data paths, and the demonstration of experimental control through prediction, verification, and replication within the design. Large, randomized control groups are characteristic of group designs, not single-case designs.
