The present invention includes a matrix associated with the influence of at least one participant. The matrix includes at least one participant and a market defining the practice area of the at least one participant, wherein the market is statistically modeled to represent the degree of influence exerted by the at least one participant. The present invention further includes a method of assessing an influence level of at least one physician. This method include forwarding at least two survey questions to a physician, wherein one of said at least two survey questions includes an allowance for naming at least one nominee physician, weighting at least one possible answer to the at least two survey questions, receiving at least one response to said at least two survey question, and placing the physician and the nominee physician in a referral tree at a hierarchical level in accordance with said weighting accorded the responses.