A Generalization of Wendell's Tolerance Approach to Sensitivity Analysis in Linear Programming

A criticism of linear programming has been that the data which are available in practice are too inexact and unreliable for linear programming to properly work. Managers are therefore concerned with how much actual values may differ from the estimates that were used in the model before the results become irrelevant. Sensitivity analysis emerged to help deal with the uncertainties inherent in the linear programming model. However, the ranges calculated are generally valid only when a single coefficient is varied. An extension of sensitivity analysis, the 100 Percent Rule, allows the simultaneous variation of more than one element in a vector, but does not permit the independent variation of the elements. A tolerance approach to sensitivity analysis enables the consideration of simultaneous and independent change of more than one coefficient. However, the ranges developed are unnecessarily restricted and may be reduced in width to zero when primal or dual degeneracy exists. This paper presents an extension of the tolerance approach which reduces the limitations of both the traditional and tolerance approaches to sensitivity analysis.     

Foreign-born emigration: A new approach and estimates based on matched CPS files

The utility of postcensal population estimates depends on the adequate measurement of four major components of demographic change: fertility, mortality, immigration, and emigration. Of the four components, emigration, especially of the foreign-born, has proved the most difficult to gauge. Without "direct" methods (i.e., methods identifying who emigrates and when), demographers have relied on indirect approaches, such as residual methods. Residual estimates, however are sensitive to inaccuracies in their constituent parts and are particularly ill-suited for measuring the emigration of recent arrivals. Here we introduce a new method for estimating foreign-born emigration that takes advantage of the sample design of the Current Population Survey (CPS): repeated interviews of persons in the same housing units over a period of 16 months. Individuals appearing in a first March Supplement to the CPS but not the next include those who died in the intervening year, those who moved within the country, and those who emigrated. We use statistical methods to estimate the proportion of emigrants among those not present in the follow-up interview. Our method produces emigration estimates that are comparable to those from residual methods in the case of longer-term residents (immigrants who arrived more than 10 years ago), but yields higher--and what appear to be more accurate--estimates for recent arrivals. Although somewhat constrained by sample size, we also generate estimates by age, sex, region of birth, and duration of residence in the United States.     

Multi-Item Grouping Algorithm Yielding Near-Optimal Logistics Cost

This article describes an algorithm used to formulate an inbound consolidation strategy when multi-items are replenished in groups and when total logistics cost is to be minimized. The importance of this algorithm is threefold (1) no optimal procedure exists for grouping multi-items when minimizing total logistics cost, (2) a complete enumeration of all possible groups (from which the optimal grouping set can be identified) is impractical due to the combinatorial nature of the grouping problem, and (3) no other heuristics have been developed that adequately reflect shipping cost in the analysis like this one does. We report the experience of using this algorithm to group and reorder 75 selected ensembles containing a total of 517 inventory items of a retail merchandising firm.     

Correction to: Climate variability and health in extremely vulnerable communities: investigating variations in surface water conditions and food security in the West African Sahel

Population and Environment - A correction to this paper has been published: https://doi.org/10.1007/s11111-021-00381-x     

What makes a Gael? Identity,language and ancestry in the Scottish Gàidhealtachd

Scholars know far less about ‘national identity’ than ‘nations’ and ‘nationalism’. The authors argue that the concept is sociologically important and briefly discuss its relationship with language. They examine empirically how people living in the Gàidhealtachd, the area of Scotland associated with Gaelic language and culture, whether they are Gaelic speakers or not, whether incomers or not, go about their territorial identity business. The article shows how respondents’ Gaelic identity relates to their British and Scottish identity; how people living in the Gàidhealtachd assess putative claims to a Gaelic identity based variously on language, residence and ancestry; and how they see the balance between ‘cultural’ and ‘political’ elements in Gaelic. The authors argue that to study ‘what makes a Gael?’ highlights the key role territorial identity plays in connecting social structure to social action, and also that identity provides a set of meanings and understandings through which people experience social structure and feel empowered to act.     

The adoption of multiple certification standards: perceived performance implications of quality,environmental and health & safety certifications

This study assesses the combined impact of multiple certifications (i.e. ISO 9001, ISO 14001, OHSAS 18001) on perceived performance dimensions related to quality, environmental and occupational health and safety. Using survey data collected from 59 Irish manufacturing plants in 2014, we employed MANCOVA and regression analysis to test our proposed hypothesis. The results suggest that companies that are simultaneously ISO 9001, ISO 14001 and OHSAS 18001 certified are significantly better performers with regard to environmental and occupational health and safety compared to companies without multiple certifications. However, from a perceived quality performance perspective, having these multiple certifications doesn’t seem to be an effective performance improvement tool.     

Invariant co-ordinate selection

Summary.  A general method for exploring multivariate data by comparing different estimates of multivariate scatter is presented. The method is based on the eigenvalue–eigenvector decomposition of one scatter matrix relative to another. In particular, it is shown that the eigenvectors can be used to generate an affine invariant co-ordinate system for the multivariate data. Consequently, we view this method as a method for invariant co-ordinate selection . By plotting the data with respect to this new invariant co-ordinate system, various data structures can be revealed. For example, under certain independent components models, it is shown that the invariant co- ordinates correspond to the independent components. Another example pertains to mixtures of elliptical distributions. In this case, it is shown that a subset of the invariant co-ordinates corresponds to Fisher's linear discriminant subspace, even though the class identifications of the data points are unknown. Some illustrative examples are given.     

Contagion of Anxiety Symptoms Among Adolescent Siblings: A Twin Study

This study examined whether social contagion of anxiety symptoms is present between siblings during early adolescence and whether this process is moderated by sex, relationship quality, and zygosity. Based on 634 monozygotic and dizygotic twins (336 females) assessed in Grades 6 and 7, anxiety symptoms and sibling relationship quality were measured with self‐report questionnaires. The predictive association of the co‐twin's level of anxiety with adolescents' own increased anxiety 1 year later was only observed in same‐sex twin dyads (monozygotic and dizygotic) and was higher for those who perceived a higher level of relationship quality with their co‐twin. Raising awareness of a possible sibling contagion of anxiety may be useful for preventing the development of anxiety symptoms in youth.     

Dementia: challenges for social work education in Europe

ABSTRACT

Dementia has been identified as a global challenge across the spectrum of health and social care (World Health Organisation. (2012) Dementia: A public health priority. Geneva: WHO). This paper will explore the implications of this for social work education and the challenges it poses. There is a lack of this focus on social work with older people and people with dementia (pwd) in social work education. Based on calls for an infusion of content on ageing and dementia in social work curricula, paper proposes that we should adopt a person-centred philosophy alongside gerontological social work competencies to achieve this. The specific aim of this paper, therefore, is to explore how we can use these ideas as teaching tools to engage social work students in the discourse on dementia and to develop appropriate skills to work with pwd, their families and carers.     

The Divide Between “Evidenced‐Based” Approaches and Practitioners of Traditional Theories of Family Therapy

Evidenced‐based approaches continue to grow in the field of family therapy. However, practicing family therapists do not always embrace these approaches. In this article, we explore factors contributing to practitioners' concerns with evidence‐based treatments and suggest a broader, more clinically palatable view of evidenced‐based treatment. We also suggest how family therapy researchers, practitioners, and educators might begin to close the researcher–clinician divide in the best interest of all concerned.