The Rasch model and other latent trait models encounter some difficulty when faced with an appreciable amount of missing data or omitting behavior. The present note assumes that some reasonable missing data model has been formulated which does not involve the parameters associated with the latent ability of interest. A maximum likelihood function…

This research deals with optimizing the instructional process. The approach adopted was to limit consideration to simple learning tasks for which adequate mathematical models could be developed. Optimal or suitable suboptimal instructional strategies were developed for the models. The basic idea was to solve for strategies that either maximize the…

PIAGET'S THEORETICAL FORMULATION OF THE DEVELOPMENT OF CONSERVATION OF CONTINUOUS QUANTITY WAS EXAMINED. CONTROL SUBJECTS IN EACH OF TWO AGE GROUPS (5 AND 6 YEARS) WERE GIVEN A COMPLEX TASK SITUATION THAT IS TYPICAL OF PIAGET'S WORK. THESE SUBJECTS WERE ALSO GIVEN ANOTHER TASK, A MEASURE OF CONSERVATION OF QUANTITY THAT IS INDEPENDENT OF PIAGET'S…

Focuses on developing a systematic characterization of the error forms resulting from model misspecification in single equation models for least squares regression analyses. (Author/DEP)

General role structure theory is explained in algebraic models. (DE)

The calculation of concentrations in the case of many simultaneous equilibria can be reduced to a search for a local minimum of a function of n variables, in which n denotes the number of mass balances involved. The method is simple and time-saving, but requires the availability of a computer. (author/BB)

A definition of a suppressor variable is presented which is based on the relation of the semipartial correlation to the zero order correlation. Advantages of the definition are given. (Author/JKS)

Path analytic techniques for assessing the validity of indicators in multitrait-multimethod matrices represent improvements on Campbell and Fiske's early procedures for testing for validity. The diagnosis of indicator ills by means of confirmatory factor analysis is especially useful. An empirical example of these techniques is presented.…

The concepts of elevation, scatter, and shape are investigated as parameters in assessing the similarity among profiles of individuals. A computational strategy for differentiating the independent contribution of each parameter to more global indices of resemblance is presented. (Author/JKS)

The imprecision of some concepts used in formal models in information science has led to attempts to apply fuzzy set theory to aspects of information science. An analysis of various kinds of imprecision that can occur indicates that fuzzy set theory is not an appropriate formalism for these models. (Author/MBR)

Path analysis is a data analytic technique for estimating the strengths of hypothesized relationships among a group of variables for a particular sample. Strategies for the use of path analysis are discussed in detail in this extensive article. (JKS)

The concepts of demand, need, desire, and take-up were discussed in the context of preschool services in three small areas of Inner London. It was shown by using log-linear models that desire for preschool provision could be efficiently predicted by a combination of sociodemographic variables. (Author/IRT)

Presents mathematical games that involve a problem-solving matrix, multicolored cubes, and three-dimensional dominoes. The work of Alexander MacMahon is highlighted. (MA)

Examines an alternative approach to analysis of chemical reactions. In this approach, a thermal entropy gradient is introduced. (MA)

The relationship between quantitative predictor variables and the probability of occurrence of one or more levels of a qualitative criterion variable can be analyzed by quantal response techniques. This paper presents and discusses two quantal response models, comparing them to multiple linear regression and discriminant analysis. (Author/JKS)