A practitioner conducts a single-case evaluation to test whether a recently developed intervention is effective in reducing antisocial behaviors by children in a residential facility. During the 20 days before implementing the new intervention she observes between 15 and 17 antisocial behaviors each day. After implementing the intervention she observes between 15 and 17 antisocial behaviors each day for 19 days, but then on the twentieth day no antisocial behaviors occur. She should conclude:
A) The intervention clearly was effective.
B) The improvement most likely was due to maturation.
C) History is a plausible explanation for the improvement.
D) Regression to the mean is the most plausible explanation for the improvement.

Question

A practitioner conducts a single-case evaluation to test whether a recently developed intervention is effective in reducing antisocial behaviors by children in a residential facility. During the 20 days before implementing the new intervention she observes between 15 and 17 antisocial behaviors each day. After implementing the intervention she observes between 15 and 17 antisocial behaviors each day for 19 days, but then on the twentieth day no antisocial behaviors occur. She should conclude:​
A) ​The intervention clearly was effective.
B) The improvement most likely was due to maturation.​
C) History is a plausible explanation for the improvement.​
D) Regression to the mean is the most plausible explanation for the improvement.​

Quizplus · Accepted Answer

The fact that no antisocial behaviors occurred on the twentieth day suggests that an external factor may have influenced this outcome, rather than the intervention alone. History, which refers to events or changes in the environment that occur outside of the intervention that may affect the outcome, is a plausible explanation for the improvement observed. It is important for the practitioner to rule out alternative explanations before concluding that the intervention was effective.

A Practitioner Conducts a Single-Case Evaluation to Test Whether a Recently