In their study designed to investigate the relative impact of 'task and institutional influences on managers' mental models of competition,' Daniels et al. (2002) elicited cognitive maps using two complementary ideographic mapping procedures: a card-sort technique and a variant of the repertory grid. Given that the resulting individual maps were each based on differing organizations and attributes, Daniels and his colleagues assessed belief similarity - their key dependent variable - by asking their participants to rate the overall similarity of the various maps so elicited to their own mental models which prevailed at the time the comparative rating exercise was subsequently performed, some three to six months later. Drawing on research into the cognitive processes underpinning similarity judgements, I argue that this approach to the comparison of cognitive maps suffers from a number of severe limitations which are likely to bias the results in favour of the research hypotheses under test, thus leading to increased type I errors. Alternative procedures for eliciting and comparing individuals' mental representations of competition are briefly considered.