1. A method, comprising: obtaining a detected parameter value for use in classifying a posture state of a patient; for each of multiple posture state definitions, obtaining a respective defined parameter value and a respective therapy parameter value; determining, for each of a plurality of the posture state definitions, a similarity between the detected parameter value and the respective defined parameter value; determining a blended therapy parameter value based on the similarities and respective therapy parameter values for the plurality of the posture state definitions; and delivering therapy to the patient via a medical device according to the blended therapy parameter value.