A Variable Selection Criterion in the Linear Programming Approaches to Discriminant Analysis*

There are numerous variable selection rules in classical discriminant analysis. These rules enable a researcher to distinguish significant variables from nonsignificant ones and thus provide a parsimonious classification model based solely on significant variables. Prominent among such rules are the forward and backward stepwise variable selection criteria employed in statistical software packages such as Statistical Package for the Social Sciences and BMDP Statistical Software. No such criterion currently exists for linear programming (LP) approaches to discriminant analysis. In this paper, a criterion is developed to distinguish significant from nonsignificant variables for use in LP models. This criterion is based on the “jackknife” methodology. Examples are presented to illustrate implementation of the proposed criterion.     

Students’ health engagement and affective relations in Danish upper secondary school

To increase our understanding of the dynamics of young people’s embodied engagement in health, this article analyses Danish upper secondary school students’ understandings and practices of health and the role of the school environment in these dynamics. Participatory, visual and narrative data were collected during fieldwork with 37 students aged 16–17. Deleuze and Guattari’s philosophy of the body is applied to analyse the affective relations and emerging body-health assemblages within the students’ school life, which generated force and vitality (here conceptualised as health). Through becoming within sensuous, social and political body-health assemblages, the students attempted to curb school stress, sustain social belonging in an individualistic school environment and both reproduce affirming power discourses and subvert their territorialisation. The study proposes an analytical shift in perspective on young people’s health away from an individualistic ‘components approach’ towards a relational understanding, and suggests that students’ health at school relates to collectivity, quality, rhythm and co-produced engagement, rather than individuality, quantity, rules and performance, which increasingly characterise Danish health discourse and school policy.     

Observational sketching as method

This paper explores the potential of observational sketching as a social science research tool, informed by our own recent experiments with observational sketching techniques and approaches. We first outline the historical roots of academic sketching and note a recent resurgence of interest in sketching in certain disciplines. We then introduce our own explorations in sketching as method, based on a year-long collaboration between an observational artist and a group of qualitative researchers with interests in creative methods. The paper outlines some of the lessons we learnt from our partnership, focusing on three themes: (i) ‘sketchiness’; (ii) ‘concentrated seeing’ and (iii) sketching as interaction. We conclude that observational sketching generates a refreshingly different form of visual data which has considerable potential to be used as a complement to other methods, including as a participatory method and as a useful tool for thinking.     

Who needs Cantonese,who speaks? Whispers across mountains,delta, and waterfronts

This essay digs into the ‘dirtiness’ of cultural studies to prioritize praxis, or as the way my mountain folks collect summer lotus: putting our feet in the muddy water, and finding ways to get the stems underneath the smooth leaves. Using Cantoneseness as a case to locate such ‘dirtiness’, I draw on personal/familial histories as well as research projects to tell how conjunctures of Cantoneseness are politically and unevenly lived. This complex journey travels roughly from my childhood in the Yuebei mountains of northern Guangdong through my teenage and early adult years in the Pearl River Delta (PRD) to my current location as a temporary resident in the East Pacific port of Vancouver. I selectively emphasize and speak on three different locations: first, the rural inland Cantonese location of Yuebei mountains – the borderland and hinterland experiences of my family and myself living what the mountains would offer and how these have changed; second, the industrial superior Cantonese location of PRD in Shenzhen and Guangzhou – my personal experiences and identities as a migrant youth, combined with a case study including interviews with migrant peasant-workers and their children; and third, the western transnational Cantonese location of East Pacific waterfronts in Vancouver and Richmond – my personal engagement with social activism as an ethnicized, international student, combined with a narrative study including interviews with social activists with different Cantoneseness and migration routes. While this mix of whispers speaks in its own way towards using cultural studies with more seriously (global) space-sensitive and (social justice) praxis-sensitive approaches, the primary focus is more modestly on my autobiographical accounts and research efforts as a specific case: to show some strategic locations of ‘Cantonescape’ on the one hand, and to invite wider conversations around cultural-spatial politics on the other.     

Influence of Female Genital Cutting on Sexual Experience in Southern Ethiopia

Female genital cutting (FGC) is a persistent social norm in the Liben district of southern Ethiopia. This study explores whether the sexual experiences of married men and women differ by women's FGC status. Qualitative in-depth interviews were conducted with 28 women with different types of FGC (or no FGC) and 21 husbands. Compared to others, women with more severe FGC reported traumatic sexual experiences and decreased sexual desire. Nonetheless, participants largely endorsed FGC for daughters, revealing pressure to maintain the practice. Opportunities for change exist, as women and men recognized the sexual pleasure and healthy birth experiences of uncut women.     

Optimal design of the adaptive exponentially weighted moving average control chart over a range of mean shifts

The adaptive exponentially weighted moving average (AEWMA) control chart is a smooth combination of the Shewhart and exponentially weighted moving average (EWMA) control charts. This chart was proposed by Cappizzi and Masarotto (2003) to achieve a reasonable performance for both small and large shifts. Cappizzi and Masarotto (2003) used a pair of shifts in designing their control chart. In this study, however, the process mean shift is considered as a random variable with a certain probability distribution and the AEWMA control chart is optimized for a wide range of mean shifts according to that probability distribution and not just for a pair of shifts. Using the Markov chain technique, the results show that the new optimization design can improve the performance of the AEWMA control chart from an overall point of view relative to the various designs presented by Cappizzi and Masarotto (2003). Optimal design parameters that achieve the desired in-control average run length (ARL) are computed in several cases and formulas used to find approximately their values are given. Using these formulas, the practitioner can compute the optimal design parameters corresponding to any desired in-control ARL without the need to apply the optimization procedure. The results obtained by these formulas are very promising and would particularly facilitate the design of the AEWMA control chart for any in-control ARL value.     

Monotonic change point estimation of generalized linear model-based regression profiles

In this article, a maximum likelihood estimator is derived in the generalized linear model-based regression profiles under monotonic change in Phase II. The performance of the proposed estimator is comprehensively investigated through some special cases, and compared with estimators under step change and drift. The results show that the proposed estimator has better performance in small and medium shifts under different increasing changes. Finally, the applicability of the proposed estimator is illustrated using a real case.     

Statistical inference for the Gompertz distribution based on Type-II progressively hybrid censored data

In this article, the statistical inference for the Gompertz distribution based on Type-II progressively hybrid censored data is discussed. The estimation of the parameters for Gompertz distribution is obtained using maximum likelihood method (MLE) and Bayesian method under three different loss functions. We also proved the existence and uniqueness of the MLE. The one-sample Bayesian prediction intervals are obtained. The work is done for different values of the parameters. We apply the Monto Carlo simulation to compare the proposed methods, also an example is discussed to construct the Prediction intervals.