What Does it Take for a Canadian Political Scientist to be Cited?*

Objectives. The article examines the factors that influence the frequency whereby scholarly articles published by Canadian political scientists are cited. Method. We collected data on 1,860 journal articles published between 1985 and 2005 by 758 Canadian political scientists and listed in the Social Science Citation Index. Using these data, we performed OLS and tobit estimations to identify factors influencing citation frequency. Results. The regressions show that the reputation of the journal in which the article is published, though important, does not explain everything. The gender of the author(s), the number of authors, the geographical focus of the article, the field, and the methodology also matter. Conclusion. An article is more likely to be widely cited if it is published in a prestigious journal, if it is written by several authors, if it applies quantitative methods, if it compares countries, and if it deals with administration and public policy or elections and political parties. Faculty members who belong to larger departments and those who are women are more cited.     

Ordinal models and generalized estimating equations to evaluate disease severity

Many assays have been carried out in Capsicum spp. in order to evaluate its resistance to Phytophthora capsici , which causes blight and considerable yield loss. An assay aiming at the selection of resistant pepper and bell pepper genotypes to P. capsici was jointly performed in the laboratory of the Phytopathological Clinic of Entomology, Phytopathology and Agricultural Zoology and in the experimental area of the Plant Production Department, both located at ESALQ, University of São Paulo, Brazil. The data set for this assay comes from ordinal categorized random variables, whose analysis does not generally take into account the ordinal nature of the responses, but instead, builds indexes, among other measures, in order to evaluate the resistance of the studied genotypes. This work presents ordinal generalized linear fits in order to evaluate blight severity as well as to identify and select new resources to the pathogen. It also analyses the estimating equations proposed by Liang & Zeger (1986a, b) in order to obtain an infection pattern for the disease. From the fit of the cumulative logit models, valuable genotypes are identified for genetic breeding programs.     

Influence and sensitivity measures in correspondence analysis

Since correspondence analysis appears to be sensitive to outliers, it is important to be able to evaluate the sensitivity of the data on the results. This article deals with measuring the influence of rows and columns on the results obtained with correspondence analysis. To establish the influence of individuals on the analysis, we use the notion of influence curve and we propose a general criterion based on the mean square error to measure the sensitivity of the correspondence analysis and its robustness. A numerical example is presented to illustrate the notions developed in this article.     

Joint Estimation of Intersecting Context Tree Models

We study a problem of model selection for data produced by two different context tree sources. Motivated by linguistic questions, we consider the case where the probabilistic context trees corresponding to the two sources are finite and share many of their contexts. In order to understand the differences between the two sources, it is important to identify which contexts and which transition probabilities are specific to each source. We consider a class of probabilistic context tree models with three types of contexts: those which appear in one, the other, or both sources. We use a BIC penalized maximum likelihood procedure that jointly estimates the two sources. We propose a new algorithm which efficiently computes the estimated context trees. We prove that the procedure is strongly consistent. We also present a simulation study showing the practical advantage of our procedure over a procedure that works separately on each data set.     

Various Approaches for Predicting Land Cover in Mountain Areas

Using former maps, geographers intend to study the evolution of the land cover in order to have a prospective approach on the future landscape; predictions of the future land cover, by the use of older maps and environmental variables, are usually done through the GIS (Geographic Information System). We propose here to confront this classical geographical approach with statistical approaches: a linear parametric model (polychotomous regression modeling) and a nonparametric one (multilayer perceptron). These methodologies have been tested on two real areas on which the land cover is known at various dates; this allows us to emphasize the benefit of these two statistical approaches compared to GIS and to discuss the way GIS could be improved by the use of statistical models.     

The Well-Being of the Canadian Arctic Inuit: The Relevant Weight of Economy in the Happiness Equations

Which of the three dimensions of Allardt’s model, “having, loving, and being”, best predicts the incidence of subjective feeling of well-being among the Canadian Arctic Inuit adults? To answer this question, two logistic regression equations have been constructed, one based on a negative assessment of well-being (feeling of despair), and the other on a positive assessment (satisfaction with life in the community). Each of them took first the form of a global model, and then of three scale models, one for each dimension of the Allardt’s model. The equations are likely to be more effective for predicting the incidence of Inuit’s feeling of satisfaction than for anticipating their feeling of despair. Furthermore, the “being” scale model is the one that will have contributed most to the predictive performance of the global model. In other words, what the Inuit “ARE” contributes more to the incidence of their satisfaction with life than what they “HAVE” or what they “LOVE”.     

Force steadiness in the lower extremities as an independent predictor of functional performance in older women

The relationship between isometric force control and functional performance is unknown. Submaximal steadiness and accuracy were measured during a constant force-matching task at 50% of maximal isometric voluntary contraction (MVC) of the knee extensors in 19 older women (70-89 years). Other variables included MVC, rate of torque development, and EMG activity. Functional performance was assessed during maximal performance of walking endurance, chair rising, and stair climbing. Isometric steadiness (but not accuracy) was found to independently predict chair-rise time and stair-climbing power and explained more variance in these tasks than any other variable. Walking endurance was related to muscle strength but not steadiness. These results suggest that steadiness is an independent predictor of brief, stressful functional-performance tasks in older women with mild functional impairment. Thus, improving steadiness might help reduce functional limitations or disability in older adults.     

Qualité des produits alimentaires et marques de filières

Brands have recently cropped up in the distribution of fresh produce - a phenomenon closely linked to food and health crises in the past few years. Public authorities have been creating new control and monitoring procedures, tightening regulations on production and modifying regulations about official labels of quality. Meanwhile, retailers have been adopting new strategies for segmenting supply. How does this affect the supply of produce to consumers? How does it modify relations between producers and distributors? Under what conditions do these parties have an interest in complying? How do these segmentation strategies interact with the policies advocated by public officials and affect the raising of standards for a “minimum quality”? - Special issue on Agriculture and food.     

Second Unions Now More Stable than First? A Comparison of Separation Risks by Union Order in France

The frequency of union dissolutions increased sharply over the past 40 years in Western Europe and North America, resulting in a rapid growth in the number of persons living with a second partner. In studies of the 1980s, primarily conducted within the context of marriage, second partnerships were generally found to be less stable than first unions, but more recent studies provide more conflicting evidence. Taking the example of France, we study whether the relationship between first and second union stability indeed reversed between the 1970s and the 2000s, and how union and individual characteristics contributed to changes over time. The analysis presented here is based on the French Generations and Gender Survey (2005). The article first provides an overview of the differences in marriage, childbearing and breakup behaviours in first and second unions. Second, a piecewise linear model for repeated events is used to compare women’s dissolution risks in first and second unions. The results show that over time, the higher instability of second compared to first unions disappeared. Further, women in second unions adopted unmarried cohabitation as a living arrangement more often across the whole period and were more likely to have stepchildren, which was associated with less stable unions. Taking into account this diversity of family situations, i.e. controlling for family form and children, second unions were more stable than first unions, even during the past. At both union orders, marriage breakup risks tended to stabilise despite a continuing increase in the prevalence of separation, which suggests that cohabitation increasingly acts as a filter for marriage.