Using several data sets, the relative performance of the beta binomial model and two more general strong true score models in estimating several indices of classification consistency is examined. It appears that the beta binomial model can provide inadequate fits to raw score distributions compared to more general models. (TJH)

The mean and variance of the statistic psi-star, which is useful for measuring agreement between two raters and allows for tests of significance in the case of large samples, are considered. Results may also be applied for the "G" index of J. W. Holley and J. P. Guilford (1964). (SLD)

The Dutch Identity is presented as a useful tool for expressing the basic equations of item response models that relate the manifest probabilities to the item response functions and the latent trait distribution. Ways in which the identity may be exploited are suggested and illustrated. (SLD)

Statistical properties of person fit indices are reviewed as indicators of the extent to which a person's score pattern is in agreement with a measurement model. Distribution of a fit index and ability-free fit evaluation are discussed. The null distribution was simulated for a test of 20 items. (SLD)

An approach to scoring reading comprehension based on the concept of the testlet is described, using models developed for items in multiple categories. The model is illustrated using data from 3,866 examinees. Application of testlet scoring to multiple category models developed for individual items is discussed. (SLD)

Information functions are used to find the optimum ability levels and maximum contributions to information for estimating item parameters in three commonly used logistic item response models. Implications are discussed for applications such as adaptive testing and test construction. (SLD)

Use of the Mantel-Haenszel procedure as a test for differential item functioning under the Rasch model of item-response theory is examined. Results of the procedure cannot be generalized to the class of items for which item-response functions are monotonic and local independence holds. (TJH)

Recently, C. E. McCulloch (1987) suggested a modification of the Morgan-Pitman test for comparing the variances of two dependent groups. This paper demonstrates that there are situations where the procedure is not robust. A subsample approach, similar to the Box-Scheffe test, and the Sandvik-Olsson procedure are also assessed. (TJH)

Discusses the interdependencies between parameter estimation and properties of probabilistic models, such as dependency assumptions, binary vs. nonbinary features, and estimation sample selection. An optimum estimation for binary features applicable to information retrieval is defined, a method for computing this estimation using empirical data is…

Argues that a major difficulty in using Lotka's law in information science arises from the misuse of goodness of fit tests in parameter estimation. Three approaches for studying Lotka's law are presented: an index approach, a time series approach, and a generating mechanism incorporating these two influential variables to derive an equilibrium…

Two coefficients ("H" and "C") for evaluating the homogeneity or congruence of a set of ratings or scores are described. Statistical tests of the significance of these indexes are presented, along with a description of a computer program (CHOPRO) for determining values of "C" and "H" and associated…

The robustness of the likelihood ratio difference statistic to the violation of a regularity condition when used to assess differences in fit provided by pairs of latent class models was investigated. Recommendations are made regarding the use of the statistic under violation of the regularity condition. (SLD)

Two observed-score methods that assume equally reliable congeneric tests were compared for the external anchor test equating model. Each derivation was compared to existing test equating methods based on different assumptions. Using samples of Australian secondary school students (N=about 6,000), the methods were compared empirically with existing…

Discusses the master equation of a stochastic model in chemical process systems. Presents a solution technique known as the System Size Expansion. (YP)

In this analysis of 1,815 arbitration cases in British Columbia in 1982-85, bias is identified in the bivariate estimates of the probability of management wins by industry and issue. Bivariate estimate errors in these cases can result from failure of estimates to adjust for the effects of omitted variables. (TJH)