On structural equation modeling with data that are not missing completely at random

A general latent variable model is given which includes the specification of a missing data mechanism. This framework allows for an elucidating discussion of existing general multivariate theory bearing on maximum likelihood estimation with missing data. Here, missing completely at random is not a prerequisite for unbiased estimation in large samples, as when using the traditional listwise or pairwise present data approaches. The theory is connected with old and new results in the area of selection and factorial invariance. It is pointed out that in many applications, maximum likelihood estimation with missing data may be carried out by existing structural equation modeling software, such as LISREL and LISCOMP. Several sets of artifical data are generated within the general model framework. The proposed estimator is compared to the two traditional ones and found superior.The research of the first author was supported by grant No. SES-8312583 from the National Science Foundation and by a Spencer Foundation grant. We wish to thank Chuen-Rong Chan for drawing the path diagram.     

Completion norms for 40 three-letter word stems

This is a report of the completion responses for 40 three-letter word stems (e.g., ABO) produced by 100 undergraduate students at the University of California at San Diego. The report includes a list of the different words that were written as stem completions, their frequency of occurrence as completions, and their frequency of occurrence in English according to published norms. This list of materials is useful for the construction of completion tests for future investigations of direct priming phenomena, and it may provide an important covariate in the analysis of performance on completion tests. Preliminary analyses of the results reveal three primary factors that determine overall performance on a stem-completion test: word frequency, word length, and meanings per word. Analyses of the completions produced for each individual word stem, however, reveal that usually only one of these factors makes a significant contribution to performance.     

Three-dimensional perspective drawing of two-dimensional functions with microcomputers

In this paper, we present a BASIC program for Apple II series computers that allows the user to obtain perspective drawings of two-dimensional functions of known analytical expression. Also, we outline a procedure for obtaining perspective representations of two-dimensional arrays of data using the same program. The program should run on any computer with graphics mode with only slight modifications in the graphics commands.     

The role of phonemes and syllables in the perceived similarity of speech sounds for children

In two experiments, we investigated the factors that influence the perceived similarity of speech sounds at two developmental levels. Kindergartners and second graders were asked to classify nonsense words, which were related by syllable and phoneme correspondences. The results support the existence of a developmental trend toward increased attention to individual phonemic segments. Moreover, one significant factor in determining the perceived similarity of speech sounds appears to be the position of the component correspondences; attention to the beginning of utterances may have developmental priority. An unexpected finding was that the linguistic status of the unit involved in a correspondence (whether it was a syllable or a phoneme) did not seem particularly important. Apparently, the factors which contribute to the perceived similarity of speech sounds in the classification task are not identical to those which underlie performance in explicit segmentation and manipulation tasks, since in the latter sort of task, syllables are more accessible than phonemes for young children. The present task may tap a level of processing that is closer to the one entailed in word recognition and lexical access.     

Multi-agency family systems

The term 'multi-agency' family is preferred to 'disorganized' family. Multi-agency family systems present special problems of the relationships (a) within the family, (b) between family and professional network, (c) among members of the professional network and (d) between family, network and treatment centre to whom the family is referred. Pressures on the family and professional workers can create a locked system which prevents natural development of the family or effective problem solving by the workers. A systems approach to such problems is presented which includes consultation to the family/professional network system.