In some situations where reliability must be estimated it is impossible to divide the measuring instrument into more than two separately scoreable parts. In such a case, neither Cronbach's coefficient alpha nor Kristof's three-part approach are satisfactory. A technique is developed for estimating reliability in such situations. (Author/BJG)

Methods for estimating the mean and variance of latent ability parameters of a normally distributed population that has been tested with Rasch model-calibrated test items are discussed. Methods for checking the normality of the population are also included. (JKS)

The Rasch model is an item analysis model with logistic item characteristic curves of equal slope, i.e. with constant item discriminating powers. The proposed goodness of fit test is based on a comparison between difficulties estimated from different scoregroups and over-all estimates. (Author)

A method for detecting instructional sensitivity (item bias) in test items is proposed. This method extends item response theory by allowing for item-specific variation in measurement relations across students' varying instructional backgrounds. Item bias detection is a by-product. Traditional and new methods are compared. (SLD)

A model developed by G. Rasch that assumes scores on some attainment tests can be realizations of a Poisson process is explained and expanded by assuming a prior distribution, with fixed but unknown parameters, for the subject parameters. How additional between-subject and within-subject factors can be incorporated is discussed. (SLD)