Patterns of Decision Making in Kidney Allocation Problems

Experts in the field of organ transplantation had to rank order a set of 32 patients according to their priority in receiving a donated kidney. The patients were described by the five characteristics that are incorporated in the kidney allocation algorithm applied by “Eurotransplant”. The priority rankings as defined by the experts were analyzed and patterns of decision making identified in the rankings investigated in this study. All patterns could be explained by some type of lexicographical ranking. The larger group of experts preordered tissue compatibility or, more technically speaking, the criterion of HLA match, while the complementary group applied the criterion of the length of waiting time first. Analyzing the finer decision structures of expert rankings and comparing the method of pattern exploration with a conjoint measurement analysis led to two follow-up questions: First, how can the value judgments of the experts be described adequately? Second, which type of aggregated ordering derived from the individual rankings represents them “best”?