A research physician wants to study the effectiveness of a new post-surgery recovery procedure. He takes a random sample of 25 surgeons from across the U.S., and asks them to recommend the technique to patients who would be a good candidate for the recovery procedure as part of the first clinical trials for this procedure. The most likely type of sampling bias in this study is: O Judgment sampling O Convenience Sampling O Volunteer samples O Incorrect Sampling Frame O Sample size bias