1. A method for evaluating therapy comprising: monitoring, with a processor, a signal generated by a sensor as a function of movement of a patient during the delivery of a therapy to the patient by a medical device that delivers the therapy to the patient according to therapy parameters that change over time according to a plurality of therapy parameter sets; identifying a plurality of movement events based on the signal during the delivery of the therapy to the patient; for each therapy parameter set in the plurality of therapy parameter sets, associating each of the movement events in the plurality of movement events that occur during the delivery of the therapy to the patient according to that particular therapy parameter set with that particular therapy parameter set; for each therapy parameter set in the plurality of therapy parameter sets, determining a value of a metric based on the movement events associated with that particular therapy parameter set, the value of the metric indicating an efficacy of that particular therapy parameter set; and storing, for each therapy parameter set in the plurality of therapy parameter sets, the value of the metric based on the movement events associated with that particular therapy parameter set in a computer-readable memory.