
Study Sample
A packet consisting of a survey instrument, a cover letter, and a postage-paid return envelope without any financial or other incentive was mailed to a random sample of 690 physicians (625 excluding pediatricians) who were listed as members of the Minnesota Medical Association (MMA) (n = 460; 418 excluding pediatricians) or the North Dakota Medical Association (NDMA) (n = 230; 207 excluding pediatricians), respectively. We used a chi-square test for the equality of two proportions to determine the original sample size of 690.























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