Fig. 1From: Evaluating the use of a recommender system for selecting optimal messages for smoking cessation: patterns and effects of user-system engagementTrend of responses over time, for users with different levels of 6-month response rate. High-response rate: > 0.6 & ≤1, Medium-response rate: > 0.1 & ≤0.6, Low-response rate: > 0 & ≤0.1Back to article page