Cost-efficient observation of working postures from video recordings--more videos, more observers or more views per observer?

In ergonomics, assessing the working postures of an individual by observation is a very common practice. The present study investigated whether monetary resources devoted to an observational study should preferably be invested in collecting many video recordings of the work, or in having several observers estimate postures from available videos multiple times. On the basis of a data set of observed working postures among hairdressers, necessary information in terms of posture variability, observer variability, and costs for recording and observing videos was entered into equations providing the total cost of data collection and the precision (informative value) of the resulting estimates of two variables: percentages time with the arm elevated <15 degrees and >90 degrees. In all 160 data collection strategies, differing with respect to the number of video recordings and the number of repeated observations of each recording, were simulated and compared for cost and precision. For both posture variables, the most cost-efficient strategy for a given budget was to engage 4 observers to look at available video recordings, rather than to have one observer look at more recordings. Since the latter strategy is the more common in ergonomics practice, we recommend reconsidering standard practice in observational posture assessment.     

Career development during childhood and adolescence

Identity development is central to the career development of children and adolescents. This article reviews the literature pertaining to identity development as being composed of career exploration, commitment, and reconsideration and offers some implications for career interventions.     

Heterogeneity and Unemployment Duration

ABSTRACT: Various unemployment duration models are estimated on a large Norwegian dataset covering labour market history 1.1.1989-31.12.1992 for all persons who became unemployed during October 1990. As many unemployed leave the unemployment register without going directly to a job, two alternative definitions of unemployment are used — register unemployment and joblessness. The problem of heterogeneity is addressed both by partitioning the individuals into four categories by previous unemployment history, and by including a random term in the job hazard. Observed as well as unobserved heterogeneity affects the estimates of expected duration to a great extent. When gamma-distributed unobserved heterogeneity is accounted for, the estimates of duration dependence become more positive relative to models where unobserved heterogeneity is ignored. Among persons who are entitled to unemployment benefit, the duration dependence appears to be significantly positive. Alternative specifications of the baseline hazard hardly affect estimates of the effects of the covariates on duration.     

Work–home conflict and facilitation across four different family structures in Norway

The purpose of this study was to examine how work–home conflict and facilitation vary among people living in different family structures in Norway, here conceptualized as: two-parent families; single parents; childless couples; and singles. The study used data from a Norwegian study on occupational health (N=2414). We hypothesized that respondents living in two-parent families experience more work–home conflict and facilitation than others due to more complex role expectations. Similarly, we hypothesized that the effect of workload and autonomy on work–home conflict and facilitation would be stronger among this group. The results indicate that conflict between work and home life are more profound among those living in two-parent families and among single parents than among childless couples and singles. Work-to-home facilitation did not vary by family structure, whereas the childless couples reported more home-to-work facilitation. Furthermore, with a few exceptions the effects of workload and autonomy on work–home conflict and facilitation did not differ by family structure.     

Are women over-represented in dead-end jobs? A Swedish study using empirically derived measures of dead-end jobs

It has been claimed that women experience fewer career opportunities than men do mainly because they are over-represented in ‘Dead-end Jobs’ (DEJs). Using Swedish panel data covering 1.1 million employees with the same employer in 1999 and 2003, measures of DEJ are empirically derived from analyses of wage mobility. The results indicate that women are over-represented in DEJs, especially in the public sector. The findings are interesting from (a) a methodological viewpoint, as it is indicated that the career opportunities associated with occupations can be indicated using one measure for both men and women, (b) the glass ceiling perspective, which arguably under-emphasizes gender inequality in relation to low positions, and (c) a class perspective, which basically ignores gender and sector in explaining career chances.

Modeling the welfare impacts of agricultural policies in developing countries

This paper presents a new model incorporating features of developing country agriculture likely to shape the welfare outcomes of alternative agricultural policies. The model features heterogeneous households linked through markets in a rural economy-wide structure, with endogenous market participation for farmers facing transactions costs. We use it to simulate the impacts on rural welfare of market price supports, production subsidies, input subsidies, and the removal of transaction costs. Applications to six countries demonstrate the diversity of potential impacts, exhibit some systemic differences compared with impacts in developed countries, and identify specific circumstances under which market interventions may be only slightly less efficient than direct payments at transferring incomes to rural households.     

Theoretical evaluation of prediction error in linear regression with a bivariate response variable containing missing data

Methods for linear regression with multivariate response variables are well described in statistical literature. In this study we conduct a theoretical evaluation of the expected squared prediction error in bivariate linear regression where one of the response variables contains missing data. We make the assumption of known covariance structure for the error terms. On this basis, we evaluate three well-known estimators: standard ordinary least squares, generalized least squares, and a James–Stein inspired estimator. Theoretical risk functions are worked out for all three estimators to evaluate under which circumstances it is advantageous to take the error covariance structure into account.     

Environmental Concern of Labor Union Members in the United States

The labor and environmental movements have had a complicated relationship with periods of cooperation as well as conflict, but recently there has been increasing collaboration at the national level. Whether such a trend of cooperation can be sustained will partially depend on grassroots‐level connections between the two movements. However, there has been little empirical research on the environmental attitudes of union members, which is important for understanding the potential for shared values between union members and environmental activists. This article analyzes 1993, 2000, and 2010 General Social Survey data to examine if the environmental attitudes of people in union households have changed given shifting labor–environment relations and broader political‐economic conditions. We find that union membership does not influence environmental concern in weaker economic times (1993 and 2010) but that it has a positive effect on environmental concern in stronger economic times (2000). Thus, union households are generally no less concerned about the environment than nonunion households. Therefore, strengthening connections between union members and environmental activists may be a feasible strategy for invigorating both the labor and environmental movements.     

Characterization of dose‐response for count data using a generalized MCP‐Mod approach in an adaptive dose‐ranging trial

Understanding the dose–response relationship is a key objective in Phase II clinical development. Yet, designing a dose‐ranging trial is a challenging task, as it requires identifying the therapeutic window and the shape of the dose–response curve for a new drug on the basis of a limited number of doses. Adaptive designs have been proposed as a solution to improve both quality and efficiency of Phase II trials as they give the possibility to select the dose to be tested as the trial goes. In this article, we present a ‘shapebased’ two‐stage adaptive trial design where the doses to be tested in the second stage are determined based on the correlation observed between efficacy of the doses tested in the first stage and a set of pre‐specified candidate dose–response profiles. At the end of the trial, the data are analyzed using the generalized MCP‐Mod approach in order to account for model uncertainty. A simulation study shows that this approach gives more precise estimates of a desired target dose (e.g. ED70) than a single‐stage (fixed‐dose) design and performs as well as a two‐stage D‐optimal design. We present the results of an adaptive model‐based dose‐ranging trial in multiple sclerosis that motivated this research and was conducted using the presented methodology. Copyright © 2015 John Wiley & Sons, Ltd.