Clinical Usefulness

Abstract

In addition to performance measures such as discrimination and calibration, we may want to know whether a prediction model is clinically useful: Is the model beneficial in clinical practice to guide diagnostic work-up, or decision making, on therapy. For such decisions, we need a cutoff for the predicted probability (``decision threshold,'' or ``classification cutoff,'' see Chap. 2). Patients with predictions above the cutoff are classified as positive; those under the cutoff as negative. We will use the term clinical usefulness for a model's ability to make such classifications better than a default policy without the prediction model.