Describes a computer simulation of the evolution of species. This is a model for sorting out random and correlated paleontological events. (BB)

A multiple time series is defined as the sum of an autoregressive process on a line and independent Gaussian white noise or a hyperplane that goes through the origin and intersects the line at a single point. This process is a multiple autoregressive time series in which the regression matrices satisfy suitable conditions. For a related article…

Argues that comparison of "effects coefficients" derived from path analysis is the preferred method of assessing the relative impact of different independent variables on a given dependent variable. Available from: American Political Science Association, 1527 New Hampshire Avenue, N.W., Washington, DC 20036; $10.50 single copy.…

The hypothesis that fluid intelligence is equivalent to the factor of general intelligence is investigated using LISREL to specify higher-order models in reanalyses of three sets of psychometric data from subjects 11, 13, and 15 years old. The three studies showed fluid intelligence to be equivalent with a general factor. (LMO)

A two-stage generalized least squares model is developed for estimating the linear regression of an individual outcome on a group characteristic in studies of multilevel data. Results of this model are compared to the results of analytic methods, and formulas are developed for assessing the accuracy of the traditional approaches. (Author/JAZ)

The model of the decision system in Murdock's two-stage memory- and-decision model for item recognition is developed and tested. The decision model is shown to be able to fit the accuracy and mean response latency data from four major recognition paradigms (Sternberg, study-test, continuous, and prememorized list). (Author/LMO)

Tests are proposed for testing the conditional independence assumption without first specifying a parametric form for the nondecreasing item characteristic curves. In an example, the conditional independence hypothesis is rejected for all possible forms of monotone item characteristic curves. (Author/BW)

Presents a model that places Boolean database queries into conjunctive normal form, thereby allowing probabilistic ranking of documents and the incorporation of relevance feedback. Experimental results compare the performance of a sequential learning probabilistic retrieval model with the proposed integrated Boolean probabilistic model and a fuzzy…

Fifteen FORTRAN 77 programs are contained in the described package. Three programs are available for each of five forgetting models involving 5, 7, 8, 9, and 10-parameter models. The programs compute parameter estimates and test parameter estimates both between and within experimental conditions. (Author/GDC)

Proposes a new definition of the nuclear zone of a Bradford or Leimkuhler curve. The mathematical rationale is outlined, and examples of the application of this technique to citation analysis are given. (15 references) (CLB)

Presents a model, using mathematical formulas, to help educational planners and administrators with the problem of allocating limited resources for general and vocational education. (MLF)

Provides an introduction to loglinear analysis of cross-classification tables, including tables with nominal and ordinal variables. Compares the chi-square test of independence with the loglinear model of independence. Reviews the advantages and overall strategy of loglinear modeling. Each model discussed is applied to data from the developmental…

Confirmatory factor analysis was applied to test second- and higher-order factor models in the areas of structure of abilities, allometry, and the separation of specific and error variance estimates. The estimation of validity and reliability, second-order models within factor analysis models, and the concept of discriminability were also studied.…

When the parameters of item response data are estimated by a latent trait model, some variation will remain unaccounted. If baseline graphical configurations of the residual variation can be constructed, measurement irregularities may be exposed. An analytic strategy for the graphical representation and analysis of Rasch model residuals is…

The properties of nonmetric multidimensional scaling one explored by specifying statistical models, proving statistical consistency, and devloping hypothesis testing procedures. Statistical models with errors in the dependent and independent variables are described for quantitative and qualitative data. (Author/LMO)