HEART first decomposes a high-level usability goal (such as “my app is awesome”) into subgoals, abstract “signals” that could measure those subgoals (e.g., time spent with app), and specific metrics for those signals (e.g., number of shares or number of articles read in app). In addition to this goals-signals-metrics breakdown, the HEART framework splits usability into five dimensions: happiness, engagement, adoption, retention, and task success.
