Residual analysis for spatial point processes (with discussion)

Summary.  We define residuals for point process models fitted to spatial point pattern data, and we propose diagnostic plots based on them. The residuals apply to any point process model that has a conditional intensity; the model may exhibit spatial heterogeneity, interpoint interaction and dependence on spatial covariates. Some existing ad hoc methods for model checking (quadrat counts, scan statistic, kernel smoothed intensity and Berman's diagnostic) are recovered as special cases. Diagnostic tools are developed systematically, by using an analogy between our spatial residuals and the usual residuals for (non-spatial) generalized linear models. The conditional intensity λ plays the role of the mean response. This makes it possible to adapt existing knowledge about model validation for generalized linear models to the spatial point process context, giving recommendations for diagnostic plots. A plot of smoothed residuals against spatial location, or against a spatial covariate, is effective in diagnosing spatial trend or co-variate effects. Q – Q -plots of the residuals are effective in diagnosing interpoint interaction.     

Comparing Networks Across Space and Time, Size and Species

We describe and illustrate methodology for comparing networks from diverse settings. Our empirical base consists of 42 networks from four kinds of species (humans, nonhuman primates, nonprimate mammals, and birds) and covering distinct types of relations such as influence, grooming, and agonistic encounters. The general problem is to determine whether networks are similarly structured despite their surface differences. The methodology we propose is generally applicable to the characterization and comparison of network–level social structures across multiple settings, such as different organizations, communities, or social groups, and to the examination of sources of variability in network structure. We first fit a p^* model (Wasserman and Pattison 1996) to each network to obtain estimates for effects of six structural properties on the probability of the graph. We then calculate predicted tie probabilities for each network, using both its own parameter estimates and the estimates from every other network in the collection. Comparison is based on the similarity between sets of predicted tie probabilities. We then use correspondence analysis to represent the similarities among all 42 networks and interpret the resulting configuration using information about the species and relations involved. Results show that similarities among the networks are due more to the kind of relation than to the kind of animal.     

The Texaco racial discrimination case and shareholder wealth

We analyze the wealth ejfects of the Texaco racial discrimination lawsuit both on the shareholders of Texaco and its major U.S. competitors. Employing a comprehensive data set which included every case docket entry and every Wall Street Journal article on the case as an experimental stimulus, our findings suggest that the overall cost of the case to Texaco shareholders exceeded $500 million, that Texaco's tribulations had little, if any, impact on the share prices of its major competitors, and that Wall Street Journal coverage of the case was highly correlated with significant changes in Texaco stock prices. This last finding provides significant support for Hite 's suppostion that newspaper editors “key ” on ex post stock price changes in selecting the events to be covered in the next day's edition. The authors are grateful to Kee Chung for helpful comments on earlier drafts and also acknowlege the help-ful assistance of the staff of the law library at the Cecil C. Humphreys School of Law at The University of Memphis.     

English Language Proficiency of Immigrants and Refugees in the Twin Cities Metropolitan Area

Studies of the determinants of English language ability have generally focused on the largest immigrant groups in the United States. Much less is known about smaller, but significant regional concentrations of immigrants and refugees. This article presents data on four very distinct and understudied groups: Russians, Somalis, Hmong, and Mexicans in the Midwest. We found large differences in English language proficiency across the different national origin groups, even after controlling for background variables. These differences were not attributable to refugee status or to linguistic distance from English. Being Somali, migrating to the United States at a young age and having a college diploma were the best predictors of both spoken and written proficiency. The returns to higher education were particularly noteworthy — respondents with college diplomas were more than 29 times more likely than non‐high school graduates to speak English well, and more than 20 times as likely to read well. Women appear to have benefited more than men from completing college in terms of spoken English proficiency since the male‐female gap narrows among the highly educated. Length of time in the United States was a good predictor of whether an individual speaks English at home, regardless of age of entry to the country.     

'The Tribunal was the most stressful thing: more stressful than my son's diagnosis or behaviour': the experiences of families who go to the Special Educational Needs and Disability Tribunal (SENDisT)

It is more than 10 years since the Special Educational Needs Tribunal was established in 1994 as an independent panel which arbitrates in disputes between parents of children with the label special educational needs and Local Education Authorities (LEAs) in England. In 2002 the Tribunal began hearing claims for disability discrimination and was re-named the Special Educational Needs and Disability Tribunal (SENDisT). Since 1994 over 20,000 appeals have been registered. This article, which forms part of my ongoing Ph.D. thesis 'Parents as advocates: the experience of parents who register an appeal with SENDisT', offers an analysis of parents' Tribunal stories. Here, the key question is what affect the process of going to SENDisT has on the social, emotional and financial well-being of the family. Through a process of narrative inquiry the aim is to foreground parents' unheard stories and to reveal their 'hidden' experiences.     

The NTEE classification system: tests of reliability/validity in the field of higher education

An analysis of the field of higher education reveals a surprisingly large number of classification errors within the (US) National Taxonomy of Exempt Entities database. Of the nearly 4,000 non-profit entities coded within the universe of institutions of higher education, we estimate that approximately 60 per cent were incorrectly included (Type II errors). Institutions incorrectly excluded from the higher education universe (Type I errors) represent roughly 10 per cent of the institutions coded correctly. These errors result primarily from assigning codes on the basis of the names of organisations (for example, College Park Towers is classified as a college, when it is in fact a housing complex for senior citizens) and from trying too hard to assign codes in ambiguous situations. The consequences can be significant for the users of these data, and we recommend raising bright warning flags while simultaneously enlisting the help of the entire non-profit sector in improving the classification coding process.The authors are with The Andrew W. Mellon Foundation. In addition to our colleagues on the staff of the Foundation, we wish to thank Helmut Anheier, Ted Bozovich, Harvey Dale, Virginia Hodgkinson, Stephen Noga and Christopher Toppe for helpful suggestions.