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