What type of data is crucial in evaluating the effectiveness of an intervention?

Quantitative data on behavior changes is essential for evaluating the effectiveness of an intervention because it provides measurable evidence of a behavior's frequency, duration, or intensity. This form of data allows practitioners to track specific behaviors before, during, and after the implementation of an intervention, facilitating objective comparisons of progress and outcomes.

Using quantitative data enables practitioners to apply statistical analyses, making it possible to identify trends, effectiveness, and the degree to which the behavior has changed. This evidence-based approach is crucial in applied behavior analysis, as it supports data-driven decision-making and ensures that interventions are adjusted based on real, observable metrics rather than assumptions or subjective feedback.

In contrast, personal opinions about behavior, abstract notions of progress, or qualitative feedback from non-participants do not provide the concrete, measurable evidence necessary to fully assess an intervention's impact. These forms of data can be more subjective and may not accurately reflect actual behavior changes, which is why they are less reliable than quantitative data for this purpose.