What aspect can lead to the conclusion that a health message was effective despite having no measurable effects?

The assertion that a health message was effective can stem from its ability to reinforce desired behaviors, even if there are no measurable effects. This concept is grounded in the idea that reinforcing existing positive behaviors can strengthen the likelihood of those behaviors being maintained over time. For example, if a health campaign consistently encourages individuals to practice good hygiene or regular exercise, and individuals report or demonstrate a continuation of these habits, it illustrates the campaign's success in reinforcing those behaviors, regardless of hard metrics that might capture immediate changes.

While the other options provide valuable effects of a health message, they do not directly support the notion of measuring effectiveness through behavioral reinforcement. Increased awareness, for instance, is a critical first step in health communication but doesn't guarantee that the audience will take action or maintain behaviors. Negative reinforcement refers to the removal of an unpleasant stimulus when a desired behavior is displayed, which may not always align with the goals of a health message. Community engagement, though important for creating a supportive environment, similarly does not inherently measure the reinforcement of specific health behaviors. Therefore, the ability to reinforce positive behavior establishes a strong foundation for determining the effectiveness of a health message even in the absence of measurable change.