Final study disposition for physicians and physician assistants, Health Care Provider Survey, Washington State, 2006. Response rates are presented as the range of unadjusted to adjusted percentages. Unadjusted response rate is the proportion of surveys completed by total number of eligible providers; nonrespondents are included in the denominator. Adjusted response rate assumes that the proportion of nonrespondents is equivalent to the proportion of providers for whom eligibility or ineligibility could be determined. This proportion for physicians was 85% (completed plus refused divided by total sample with nonrespondents removed). We considered 85% of the 176 nonrespondents as "likely eligible" (n = 150). Therefore, the denominator for the physicians' adjusted response rate was the sum of completed surveys plus refused plus "likely eligible" (n = 713). The analogous proportion for physician assistants was 67%. Ineligible returns include those not meeting study inclusion criteria and surveys returned as undeliverable. Abbreviations: WSMA, Washington State Medical Association; WADOH, Washington State Department of Health.