Research Objective. To track response rates across time for surveys of pediatricians, to explore whether response bias is present for these surveys, and to examine whether response bias increases with lower response rates. Data Source/Study Setting. A total of 63,473 cases were gathered from 50 different surveys of pediatricians conducted by the American Academy of Pediatrics (AAP) since 1994. Thirty-one surveys targeted active U.S. members of the AAP, six targeted pediatric residents, and the remaining 13 targeted AAP-member and nonmember pediatric subspecialists. Information for the full target samples, including nonrespondents, was collected using administrative databases of the AAP and the American Board of Pediatrics. Study Design. To assess bias for each survey, age, gender, location, and AAP membership type were compared for respondents and the full target sample. Correlational analyses were conducted to examine whether surveys with lower response rates had increasing levels of response bias. Principal Findings. Response rates to the 50 surveys examined declined significantly across survey years (1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002). Response rates ranged from 52 to 81 percent with an average of 68 percent. Comparisons between respondents and the full target samples showed the respondent group to be younger, to have more females, and to have less specialty-fellow members. Response bias was not apparent for pediatricians' geographical location. The average response bias, however, was fairly small for all factors: age (0.45 years younger), gender (1.4 percentage points more females), and membership type (1.1 percentage points fewer specialty-fellow members). Gender response bias was found to be inversely associated with survey response rates (r 5 À 0.38). Even for the surveys with the lowest response rates, amount of response bias never exceeded 5 percentage points for gender, 3 years for age, or 3 percent for membership type. Conclusions. While response biases favoring women, young physicians, and nonspecialty-fellow members were found across the 52-81 percent response rates examined in this study, the amount of bias was minimal for these factors that could be tested. At least for surveys of pediatricians, more attention should be devoted by investigators to assessments of response bias rather than relying on response rates as a proxy of response bias.

Children with gaps in health insurance coverage commonly do not seek medical care, including preventive visits, and do not get prescriptions filled. These findings are important for both research and policy and point to the need for more encompassing and sensitive measures of the situation of being uninsured.

This study found that low payment, capitation, and paperwork concerns all relate to low Medicaid participation by primary care office-based pediatricians. It behooves state policy makers to address these 3 factors to ensure sufficient primary care physician capacity to serve appropriately children who are enrolled in state Medicaid programs.

Compared with what non-URM pediatricians report, URM pediatricians report caring for significantly (P =.001) more minority and poor and uninsured patients. Given the few pediatricians who are URM, non-URM pediatricians should be adequately prepared to provide care for minority patients, as the proportion of minority children is high and will be increasing significantly in the next several years. Most important, efforts to ensure a racially and ethnically diverse health care workforce should be greatly enhanced, as its diversity, and hence representativeness, will improve the health care system for all Americans.

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