Although stroke survivors are the largest consumer group for postacute rehabilitation services, there has been little quantification of the details of poststroke rehabilitation (PSR), with the major exception of the AHCPR Clinical Practice Guidelines #16 of 1995. The gold standard research methodology of a randomized controlled trial cannot practically encompass PSR. Using clinical practice improvement (CPI), a statistically based, validated research methodology, a mathematical representation of the inpatient stroke rehabilitation experience has been constructed. This article examines the principle aspects of CPI methodology and how it was adapted to a multicenter study of inpatient PSR.