Agencies and practitioners often test innovative strategies for improving driver compliance with traffic regulations. However, in evaluating these strategies, researchers often rely on simple before-and-after methods that suffer from several flaws and that can result in misleading results and an inaccurate assessment of a strategy's effectiveness. This paper examines these flaws, proposes a framework that avoids or corrects for them, and then uses it to analyze the effectiveness of a common strategy: installation of larger signage (at a freeway entrance ramp). The framework described in this paper can be applied to a wide range of driver compliance situations. Among them are yielding at pedestrian crossings, speed limit obedience, and proper anticipation of roadway features such as speed humps or intersections.