Instead of providing scores for a single question, some category scaling procedures analyze the properties of the measurement as a whole. These are the response-centered approaches that provide scale values for individual respondents, rather than for items. A method sometimes used in measuring functional abilities is Guttman’s approach to what was originally called “scalogram analysis” (see Glossary). This procedure identifies groups of questions that stand in a hierarchy of severity. Where questions form a Guttman scale, an affirmative reply to a question indicating severe disability will also imply an affirmative reply to each question lower on the scale, so a person’s health status can be summarized by noting the question at which the replies switch from affirmative to negative. This pattern of responses provides evidence that the items measure varying levels of a single aspect or dimension of health, such as functional disability rather than pain due to a limb problem that affects walking ability. Thus, applied during the item analysis phase of test development, the Guttman approach helps to identify questions that do not fit the set of questions and should be discarded. Instruments that use Guttman scaling include Meenan’s Arthritis Impact Measurement Scale and Lawton and Brody’s Physical Self- Maintenance Scale. This approach is less well suited to the measurement of psychological attributes, which seldom form cumulative scales (43, p75).