Using unlabelled data to update classification rules with applications in food authenticity studies

Summary.  An authentic food is one that is what it purports to be. Food processors and consumers need to be assured that, when they pay for a specific product or ingredient, they are receiving exactly what they pay for. Classification methods are an important tool in food authenticity studies where they are used to assign food samples of unknown type to known types. A classification method is developed where the classification rule is estimated by using both the labelled and the unlabelled data, in contrast with many classical methods which use only the labelled data for estimation. This methodology models the data as arising from a Gaussian mixture model with parsimonious covariance structure, as is done in model-based clustering. A missing data formulation of the mixture model is used and the models are fitted by using the EM and classification EM algorithms. The methods are applied to the analysis of spectra of food-stuffs recorded over the visible and near infra-red wavelength range in food authenticity studies. A comparison of the performance of model-based discriminant analysis and the method of classification proposed is given. The classification method proposed is shown to yield very good misclassification rates. The correct classification rate was observed to be as much as 15% higher than the correct classification rate for model-based discriminant analysis.     

Body Weight and Matching With a Physically Attractive Romantic Partner

Matching and attribute trade are two perspectives used to explain mate selection. We investigated patterns of matching and trade, focusing on obesity, using Add Health Romantic Pair data (N = 1,405 couples). Obese individuals, relative to healthy weight individuals, were less likely to have physically attractive partners, with this disadvantage greater for women than men, and greater for White women than Black women. Additional education, a more attractive personality, and better grooming increased the probability of having a physically attractive partner and offset the disadvantage of obesity for some individuals. Unexpectedly, we found women, like men, trade education for their partners’ physical attractiveness. Despite evidence of attribute trade, matching with respect to physical characteristics was the dominant mate selection pattern.     

Zusammenfassungen

Ohne Zusammenfassung     

Bringing Two Worlds Together: A Collaborative Interview With JoEllen Patterson

JoEllen Patterson is Professor in the Marital and Family Therapy Program at the University of San Diego. She is also an Associate Clinical Professor of Family Medicine and Psychiatry at the University of California, San Diego, directing a medical family therapy clinic embedded in a Family Medicine residency (equivalent to General Practice in New Zealand). She also works in Pediatrics and Reproductive Medicine at UCSD. At present her work involves training family therapy students and family medicine residents to do interdisciplinary work using a biopsychosocial model. Research suggests that our bodies are influenced by our mental health; our immune systems and cardiovascular systems seem especially susceptible to mind‐body interplay. JoEllen is particularly interested in how family functioning influences the mind‐body system. In 2003, JoEllen Patterson received a Fulbright Senior Scholars award to visit the Wellington School of Medicine and Health Sciences, and the Child, Adolescent and Family Service in Lower Hutt, New Zealand. She spent two weeks between the clinical service and the academic department, teaching, consulting and advising. I was lucky enough to arrange this posting and to spend time with her during it.     

Academic incentives for students can increase participation in and effectiveness of a physical activity program

The authors sought to determine whether a greater academic incentive would improve the effectiveness and student adherence to a 12-week voluntary exercise program designed to decrease students' percentage of body fat. They randomly assigned 210 students to 1 of 2 groups with different academic reward structures. The group with the greater reward structure showed better exercise adherence and lost more body fat than those without the additional incentive. These findings suggest that an academic incentive can increase overall student adherence to a voluntary exercise program and can boost the effectiveness of the program in a university environment. The findings also have potential implications for on-campus promotion of physical activity.     

Gambling Screens: Does Shortening the Time Frame Affect their Psychometric Properties?

Gambling screening tools such as the South Oaks Gambling Screen (SOGS) and a DSM-IV Screen for Gambling Problems (NODS) developed by the National Opinion Research Council have psychometrically validated lifetime and past-year versions. As research questions often dictate shorter time intervals, researchers have adapted the time frames of these instruments to their specific purposes without examining whether changing the time frame affects the psychometric properties. In this study, 3-month versions of SOGS and NODS were administered to a sample of 80 pathological gamblers (59 men, 21 women, mean age 44) seeking treatment at a state-funded facility. The 3-months versions had good internal consistency, good convergent validity with each other, with gambling behaviors assessed via the timeline followback method, and with measures of impulsivity. The 3-month versions also showed good discriminant validity with demographic variables and a measure of verbal IQ. Together the data indicate that shortening the time frame to 3 months does not seem to have adverse effects on the psychometric properties of SOGS and NODS. Thus these adapted versions could profitably be used for shorter time intervals, including as pre/post-treatment and follow-up measures in treatment outcome studies.     

Anthropological versus sociological approaches to the study of soccer hooliganism: some critical notes

It is argued that the anthropological approach, as used by Armstrong and Harris, has not generated any breakthrough in the study of soccer hooliganism. In particular, it is suggested that their use of a commonsense rather than a sociological concept of violence vitiates their analysis in several ways, contributing above all to substantial inconsistencies between some of their own empirical data and their general conclusions concerning levels of soccer-related violence. It is also contended that their critique of the ‘figurational’ or ‘process-sociological’ approach followed by the Leicester researchers is based on a confused misrepresentation of that approach. Specifically it is argued (i) that Armstrong and Harris fail to recognize the wide range of methods, including extensive participant observation, used by the Leicester group, (ii) that their attempt to cast doubt on the Leicester group's contention that the core football hooligans come predominantly from the ‘rougher’ sections of the working class is based on nothing more than a priori speculation. In this connection, Armstrong and Harris themselves provide no reliable data on the social class of soccer hooligans in Sheffield, and they seem unaware of the fact that several different sources of data appear to confirm the finding of the Leicester group, (iii) they have misunderstood both the terminology and the reasoning of the Leicester group concerning the ‘rougher’ sections of the working class and their relationship to football hooliganism.     

Guilty or not? A path model of women's sexual force fantasies

This study estimated a path model of women's forceful sexual fantasies. Constructs examined were childhood sexual abuse, feminist beliefs, sexual guilt, erotophilia, and sexual experience. The study clarifies how these factors mediate one another in relationship to forceful sexual fantasies, and is first to examine the effects of feminist beliefs on forceful sexual fantasy. Adult women (N = 261) participated by completing an online survey. A path from sex guilt to forceful sexual fantasy, mediated by erotophilia, was found, wherein low levels of sex guilt and high levels of erotophilia were found to predict forceful sexual fantasy. A direct path between childhood sexual abuse and forceful sexual fantasy was also found. The resulting model is discussed in relation to previously-proposed theories on the role of force in women's sexual fantasies.