Second-order latent growth curve models (S. C. Duncan & Duncan, 1996; McArdle, 1988) can be used to study group differences in change in latent constructs. We give exact formulas for the covariance matrix of the parameter estimates and an algebraic expression for the estimation of slope differences. Formulas for calculations of the required sample…

Discussion of models for information retrieval focuses on an application of linear algebra to text clustering, namely, a metric for measuring cluster quality based on the theory that cluster quality is proportional to the number of terms that are disjoint across the clusters. Explains term-document matrices and clustering algorithms. (Author/LRW)

Presents new methods for compressing bit matrices in large information retrieval systems which exploit possible correlations between rows of words and columns of documents. Three encoding methods are tested and compared--Shannon-Fano, arithmetic, and Huffman--and an appendix discusses binomial coefficients. (20 references) (LRW)

Presents the Semantic Vector Space Model, a text representation and searching technique based on the combination of Vector Space Model with heuristic syntax parsing and distributed representation of semantic case structures. In this model, both documents and queries are represented as semantic matrices, and retrieval is achieved by computing…

Describes research that was conducted to determine the search state patterns through which users retrieve information in hypertext systems. Use of the Markov model to describe users' search behavior is discussed, and search patterns of different user groups were studied by comparing transition probability matrices. (Contains 25 references.) (LRW)