Small-group judgment methods for determining resource-based relative values.

National telephone surveys used in the Resource-Based Relative Value Scale Study produce reliable and valid relative values of work, but phone surveys are expensive and time consuming. We evaluated three small-group processes as alternatives. We compared national survey work estimates for 38 surgical services to those generated by panels of 11 and 19 highly qualified general surgeons using 1) single-round mail survey; 2) Delphi multiple-round ratings; and 3) modified Delphi with face-to-face discussion. Single-round mail-survey ratings were closest to the national survey; average differences were 11.0% and 12.6%. Delphi feedback led to increased differences: typical values differed by 14.6% and 15.2%. Face-to-face discussion led to still further divergence (21.0%). Single-round mail survey of a small number of experts provides relative work values that compare more favorably to those of the national survey than those obtained from Delphi multiple-round ratings or modified Delphi with face-to-face discussion.