Non-random sampling methods are currently used at OPTUM to obtain participants in the Client Satisfaction Survey and also the Alternative Resource/Medical Offset Study. Although various biases are conceptually associated with the use of non-random sampling procedures, the current sampling practices at OPTUM do yield representative sampling. Specifically, analyses of over 30,000 new clients in 1995 found no meaningful differences in demographic or clinical characteristics between those who (1) agreed or did not agree to be in the sample of potential participants for the client satisfaction survey; (2) did or did not participate in the follow-up satisfaction survey; and (3) did or did not participate in the Alternative Resource Study (medical service diversion).