STRENGTHS AND LIMITATIONS OF IPSATIVE MEASUREMENT

The relative merits of ipsative measurement for multi-scale psychometr ic instruments are discussed. Standard psychometric analyses are found to be inappropriate with small numbers of scales, or sets of scales w ith strong positive intercorrelations. However, for larger sets of sca les (N similar to 30) with low average intercorrelations, ipsative dat a seems to provide robust statistical results in reliability analyses but not under factor analysis. It is argued that the potential of forc ed-choice formats to control for some of the response biases typical o f normative scales means that they could have substantial advantages w hile data from score distributions are used to show that for higher nu mbers of scales, the vast majority of profiles are not so skewed that they would be Likely to be distorted by a forced-choice response forma t. The implications for score interpretation are discussed.