Logit models and logistic regressions for social networks: I. An introduction to Markov graphs andp

Spanning nearly sixty years of research, statistical network analysis has passed through (at least) two generations of researchers and models. Beginning in the late 1930's, the first generation of research dealt with the distribution of various network statistics, under a variety of null models. The second generation, beginning in the 1970's and continuing into the 1980's, concerned models, usually for probabilities of relational ties among very small subsets of actors, in which various simple substantive tendencies were parameterized. Much of this research, most of which utilized log linear models, first appeared in applied statistics publications.But recent developments in social network analysis promise to bring us into a third generation. The Markov random graphs of Frank and Strauss (1986) and especially the estimation strategy for these models developed by Strauss and Ikeda (1990; described in brief in Strauss, 1992), are very recent and promising contributions to this field. Here we describe a large class of models that can be used to investigate structure in social networks. These models include several generalizations of stochastic blockmodels, as well as models parameterizing global tendencies towards clustering and centralization, and individual differences in such tendencies. Approximate model fits are obtained using Strauss and Ikeda's (1990) estimation strategy.In this paper we describe and extend these models and demonstrate how they can be used to address a variety of substantive questions about structure in social networks.This research was supported by grants from the Australian Research Council and the National Science Foundation (#SBR93-10184). This paper was presented at the 1994 Annual Meeting of the Psychometric Society, Champaign, Illinois, June 1994. Special thanks go to Sarah Ardu for programming assistance, Laura Koehly and Garry Robins for help with this research, and to Shizuhiko Nishisato and three reviewers for their comments. INTERNETemail addresses:pattison@psych.unimelb.edu.au (PP);stanwass@uiuc.edu (SW). Affiliations: Department of Psychology, University of Melbourne (PP); Department of Psychology, Department of Statistics, and The Beckman Institute for Advanced Science and Technology, University of Illinois (SW).     

Information search patterns for gift purchases: a cross‐national examination of gender differences

This exploratory study examines the underlying determinants as well as the dimensionality of in‐store information searches for a Christmas clothing gift, focusing specifically on the differential effect of gender on information acquisition. A self‐administered survey, containing personality, situational and standard demographic measures, was administered to actual consumers in three Western countries, shortly after the Christmas season. Confirmatory factor analysis verified that in‐store information is indeed a multidimensional construct, composed of three distinct factors: macro information search, micro information search and salesperson help. Consistent with expectations, compared to males, females tended to acquire macro and micro information to a greater extent; males were more apt to seek the assistance of store sales personnel than females. This pattern was generally robust across the three countries. Other observed gender and/or country‐sample differences are discussed. Copyright © 2002 Henry Stewart Publications Ltd.     

Response learning confounds assays of inhibitory control on detour tasks

Animal Cognition - The ability to inhibit prepotent actions towards rewards that are made inaccessible by transparent barriers has been considered to reflect capacities for inhibitory control (IC)....     

An examination of hypervigilance for external threat in individuals with generalized anxiety disorder and individuals with persecutory delusions using visual scan paths

One account of generalized anxiety disorder (GAD) is that it results from hypervigilance, manifest as excessive scanning of the external environment and preferential attention to threat. However, for individuals with GAD, there has been no direct study of scanning, and evidence for preferential attention to threat has only been found for threat-words. We therefore devised a new measure of hypervigilance. Visual scan paths were recorded of individuals with GAD (N=12) and people without a psychiatric illness (N=12) viewing complex pictures that varied in threat content. People with persecutory beliefs (N=11) also participated in the study to test the hypothesis that anxiety, via such hypervigilant cognitive processes, may contribute to the maintenance of delusions. Compared with the control group, the anxious individuals were not found either to scan excessively for or to look at threat. The anxiety group was therefore not hypervigilant for external threat, which is inconsistent with the hypervigilance model. As a consequence, the hypothesis that anxiety maintains delusions was not tested. However, additional support was found for the hypothesis that people with delusions form rapid judgements on the basis of less data-gathering than control groups who are either anxious or have no psychiatric illness.     

Linguistic correlates of social anxiety disorder

The goal of this study was to examine the linguistic correlates of social anxiety disorder (SAD). Twenty-four individuals with SAD (8 of them with a generalised subtype) and 21 non-anxious controls were asked to give speeches in front of an audience. The transcribed speeches were examined for the frequency of negations, I-statements, we-statements, negative emotion words, and positive emotion words. During their speech, individuals with either SAD subtype used positive emotion words more often than controls. No significant differences were observed in the other linguistic categories. These results are discussed in the context of evolutionary and cognitive perspectives of SAD.     

Inner speech as a learned skill

Three experiments are reported which address the problem of defining a role for inner speech. Experiments 1 and 2 establish that inner speech is acquired by normally developing readers between the ages of 8 and 11, and that both slow and fast readers show a similar pattern of acquistition, but do so at a different rate from normal readers. We suggest that the development of inner speech accompanies a strategy of reading aloud “with expression”; and that it is a manifestation of the need to prestructure oral utterances. These will thus contain the lexical items visible on the page within an appropriate prosodic envelope. Both segmental and suprasegmental phonemes contribute to meaning of spoken and, by analogy, written language. Experiment 3 showed that children at this critical point in learning to read comprehended text better when certain prosodic features were made visible on the text. Prosodic restructureing may thus be an important skill acquired by young readers as they progress toward fluent, silent adult reading.     

Validating a selection test,a predictive probability approach

The problem of inferring the validity of a selection test (x) as a predictor of some criterion (y) when completexy data are not available is investigated. The basic approach is to construct the predictive probability distribution of the unobservedy scores and then derive interval estimates of the least squares regression weights, the difference in averagey scores for selected and unselected cases, and the residual variance in predictingy fromx. Further, an approximation to the predictive distribution of the squared correlation betweenx andy in a future group is derived.     

The analysis of semigroups of multirelational systems

A finite family of binary relations on a finite set, termed here a relational system, generates a finite semigroup under the operation of relational composition. The relationship between simplifications of the semigroup of a relational system in the form of homomorphic images, and simplifications of the relational system itself is examined. First of all, the list of relational conditions establishing a relationship between a homomorphic image of the semigroup of a relational system and a simplified, or derived, version of that relational system, is reviewed and extended. Then a definition of empirical relationship is introduced (the Correspondence Definition) and it is shown how, in conjunction with a factorization procedure for finite semigroups (P. E. Pattison & W. K. Bartlett, Journal of Mathematical Psychology, 1982, in press), it leads to a systematic and efficient analysis for a relational system. Applications of the procedure to an empirical blockmodel and to a class of simple relational systems are presented.