The EM algorithm is used to derive maximum likelihood estimates for item parameters of the two-parameter logistic item response curves. The observed information matrix is then used to approximate the covariance matrix of these estimates. Simulated data are used to compare the estimated and actual item parameters. (Author/BW)

Confirmatory factor analysis is presented as providing appropriate techniques for the analysis and evaluation of questionnaires and tests if the content of the measure can be identified as consisting of groups of items, with each group measuring only a single trait. This approach is contrasted with latent trait theory which assumes (and does not…

Approximately 1200 Danish school children aged 8, 11, and 14 participated in a questionnaire study under the caption, "Why I like to read." Data from Denmark formed part of an international study, in which 12 other countries used the same questionnaire to explore various functions of reading and to compare them over different countries.…