Here we examine a new task to assess working memory for visual arrays in which the participant must judge how many items changed from a studied array to a test array. As a clue to processing, on some trials in the first 2 experiments, participants carried out a metamemory judgment in which they were to decide how many items were in working memory.…

When using linear models for cluster-correlated or longitudinal data, a common modeling practice is to begin by fitting a relatively simple model and then to increase the model complexity in steps. New predictors might be added to the model, or a more complex covariance structure might be specified for the observations. When fitting models for…

A heuristic example is presented in which parsimony as typically operationalized in indices of fit may not be desirable. In a simplex model of longitudinal data, the failure to include correlated uniquenesses relating to the same indicators on different occasions will typically lead to systematically inflated estimates of stability. (SLD)

A structural equation model is proposed with a generalized measurement part, allowing for dichotomous and ordered categorical variables (indicators) in addition to continuous ones. A computationally feasible three-stage estimator is proposed for any combination of observed variable types. Two multiple-indicator modeling examples are given.…

Structural equation models require formidable computational techniques. Testing the goodness of fit involves discrepancies between original correlations among variables and correlations estimated by solved path coefficients. A BASIC computer program which solves these problems is presented and discussed. (Author/GDC)

Path analyses of two multitrait-multimethod matrices are used as examples of the kind of information afforded by application of the technique. It is concluded that the technique should be of considerable aid to researchers who want to evaluate the convergent and discriminant validity of their measures. (Author/CTM)

Contingency analyses have been employed to assess the degree to which outcomes of successive tests of corresponding items deviate from stochastic independence. A method of adjusting contingency tables to remove the effects of subject and item inhomogeneities, is presented. The method represents a partial solution to the "Simpson's…

A variety of path models involving unmeasured variables are formulated in terms of Joreskog's general model for the analysis of covariance structures. (Author)

Since computer programs have been available for estimating and testing linear causal models, these models have been used increasingly in the behavioral sciences. This paper discusses the problem that very different causal structures may fit the same set of data equally well. (Author/LMO)

Traditionally, confirmatory factor analytic models are tested against a null model of total independence. Using randomly generated factors in a matrix of 46 aptitude tests, this approach is shown to be unlikely to reject even random factors. An alternative null model, based on a single general factor, is suggested. In addition, an index of model…

Aitkin's generalized least squares (GLS) principle, with the inverse of the observed variance-covariance matrix as a weight matrix, is applied to estimate the factor analysis model in the exploratory (unrestricted) case. It is shown that the GLS estimates are scale free and asymptotically efficient. The estimates are computed by a rapidly…

Proposes a quadratic programming, least squares solution to Carroll's weighted unfolding model with nonnegativity constraints imposed on weights. It can be used to test various hypotheses about the weighted unfolding model with or without constraints. (RC)

If one is given three or more methods of measuring three or more traits, the procedure described allows one to assess the extent to which the observation is influenced by the method and the extent to which individual differences contribute to the observations, independent of the particular method-trait combination. The procedure is illustrated.…

The application and use of hierarchical models is illustrated, using the example of the structure of attitudes toward a new product and a print advertisement. Subjects were college students who responded to seven-point bipolar scales. Hierarchical models were better than nonhierarchical models in conceptualizing attitude but not intention. (GDC)