Optimizing cost-efficiency in mean exposure assessment - cost functions reconsidered

Background: Reliable exposure data is a vital concern in medical epidemiology and intervention studies. The present study addresses the needs of the medical researcher to spend monetary resources devoted to exposure assessment with an optimal cost-efficiency, i.e. obtain the best possible statistical performance at a specified budget. A few previous studies have suggested mathematical optimization procedures based on very simple cost models; this study extends the methodology to cover even non-linear cost scenarios. Methods: Statistical performance, i.e. efficiency, was assessed in terms of the precision of an exposure mean value, as determined in a hierarchical, nested measurement model with three stages. Total costs were assessed using a corresponding three-stage cost model, allowing costs at each stage to vary non-linearly with the number of measurements according to a power function. Using these models, procedures for identifying the optimally cost-efficient allocation of measurements under a constrained budget were developed, and applied on 225 scenarios combining different sizes of unit costs, cost function exponents, and exposure variance components. Results: Explicit mathematical rules for identifying optimal allocation could be developed when cost functions were linear, while non-linear cost functions implied that parts of or the entire optimization procedure had to be carried out using numerical methods. For many of the 225 scenarios, the optimal strategy consisted in measuring on only one occasion from each of as many subjects as allowed by the budget. Significant deviations from this principle occurred if costs for recruiting subjects were large compared to costs for setting up measurement occasions, and, at the same time, the between-subjects to within-subject variance ratio was small. In these cases, non-linearities had a profound influence on the optimal allocation and on the eventual size of the exposure data set. Conclusions: The analysis procedures developed in the present study can be used for informed design of exposure assessment strategies, provided that data are available on exposure variability and the costs of collecting and processing data. The present shortage of empirical evidence on costs and appropriate cost functions however impedes general conclusions on optimal exposure measurement strategies in different epidemiologic scenarios

Inequality Regimes in Grocery Stores: Intersections of Gender, Hierarchies, and Working Conditions

This article explores the extent to which spatial and hierarchical divisions of work in grocery stores intersect with gender, and resulting inequalities in employees’ working conditions. Our empirical basis is individual and group interviews conducted with managers and employees at two grocery stores in Sweden. The theoretical concept of inequality regimes serves as an analytical tool for understanding if and how multiple intersecting processes produce and maintain inequalities in working conditions. The findings show that hierarchical and gendered inequalities are (re)created in the stores, for both permanently and temporarily employed workers. The organizing processes include a functional and gendered division of the workforce together with a division based on terms of employment mainly based on the profit generated by the goods handled in each department. The study shows how spatial divisions related to hierarchy, status, and gender intersect in creating inequalities in employees’ working conditions, career opportunities, and the physical and psycho- social working environment

Inequality Regimes in Grocery Stores: Intersections of Gender, Hierarchies, and Working Conditions

This article explores the extent to which spatial and hierarchical divisions of work in grocery stores intersect with gender, and resulting inequalities in employees’ working conditions. Our empirical basis is individual and group interviews conducted with managers and employees at two grocery stores in Sweden. The theoretical concept of inequality regimes serves as an analytical tool for understanding if and how multiple intersecting processes produce and maintain inequalities in working conditions. The findings show that hierarchical and gendered inequalities are (re)created in the stores, for both permanently and temporarily employed workers. The organizing processes include a functional and gendered division of the workforce together with a division based on terms of employment mainly based on the profit generated by the goods handled in each department. The study shows how spatial divisions related to hierarchy, status, and gender intersect in creating inequalities in employees’ working conditions, career opportunities, and the physical and psycho- social working environment

A case study evaluating the ergonomic and productivity impacts of partial automation strategies in the electronics industry

A case study is presented that evaluates the impact of partial automation strategies on productivity and ergonomics. A company partly automated its assembly and transportation functions while moving from a parallel-batch to a serial line-based production system. Data obtained from company records and key informants were combined with detailed video analysis, biomechanical modelling data and field observations of the system. The new line system was observed to have 51% higher production volumes with 21% less per product labour input and lower work-in-process levels than the old batch-cart system. Partial automation of assembly operations was seen to reduce the total repetitive assembly work at the system level by 34%. Automation of transportation reduced transport labour by 63%. The strategic decision to implement line-transportation was found to increase movement repetitiveness for operators at manual assembly stations, even though workstations were constructed with consideration to ergonomics. Average shoulder elevation at these stations increased 30% and average shoulder moment increased 14%. It is concluded that strategic decisions made by designers and managers early in the production system design phase have considerable impact on ergonomic conditions in the resulting system. Automation of transport and assembly both lead to increased productivity, but only elements related to the automatic line system also increased mechanical loads on operators and hence increased the risk for work-related disorders. Suggestions for integrating the consideration of ergonomics into production system design are made

Ergonomics in the continuous development of production systems A COPE-workshop on methods for collecting and analyzing mechanical exposure data

A workshop was arranged under the auspices of the R&D program COPE with the purpose of discussing tools by which company stakeholders can assess mechanical exposure (physical workload) as an integrated part of the development of new industrial production systems. Invited Nordic experts gave their opinions on appropriate company-based target groups, relevant exposure metrics, currently available tools, and important lines of further development. The publication contains written contributions from the experts, as well as an introductory chapter presenting the concept of integrated tool development, a summary of the plenary discussion at the workshop, and lines of future R&D inspired by the workshop.Ergonomi i produktionssystem under utveckling. En COPE-workshop om metoder för insamling och analys av data om mekanisk exponering (på engelska). Inom ramarna för FoU-nätverket COPE arrangerades en workshop i syfte att diskutera verktyg som kan användas av företagsaktörer för att bedöma mekanisk exponering (fysisk belastning) som en integrerad del av utvecklingen av nya produktionssystem i industrin. Inviterade nordiska experter gav synpunkter på lämpliga målgrupper på företagen, relevanta mått på exponering, redan tillgängliga verktyg, och viktiga framtida FoU-fågor. Skriften innehåller experternas skriftliga bidrag, samt ett introducerande kapitel som presenterar iden om integrerade verktyg, refererar plenardiskussionen på workshopen, och ger exempel på fortsatta FoU-aktiviteter som inspirerats av workshopen

Eskatologien i tidlig romersk kejsertid

The so-called Messianic thought in Virgil has often been a matter of discussion. This article stresses certain aspects of this thought, namely its eschatological and soteriological implications: The primitivistic conception of the remote past as a Golden Age, exhibited in a majority of writers in classical antiquity since Hesiod, runs forth to the time of early imperial Rome. By the Augustan poets, however, especially Virgil and Horace, the idea of world-ages is presented in a new version. Virgil claims the reappearance of the Golden Age and Augustus, whose reign in the Aeneid is closely connected with the myth of Saturn as a culture-hero, is regarded as a savior, who rescued the Roman citizens from the plague of civil wars. Moreover, as asserted by Virgil, the cyclic recurrence of world-ages has come to an end. This idea must be considered as the fulfillment of an eschatology and thus, from a typological point of view, as fundamentally identical with the corresponding Christian conception of the eschatology as a present state