Flexible Tweedie regression models for continuous data

Tweedie regression models (TRMs) provide a flexible family of distributions to deal with non-negative right-skewed data and can handle continuous data with probability mass at zero. Estimation and inference of TRMs based on the maximum likelihood (ML) method are challenged by the presence of an infinity sum in the probability function and non-trivial restrictions on the power parameter space. In this paper, we propose two approaches for fitting TRMs, namely quasi-likelihood (QML) and pseudo-likelihood (PML). We discuss their asymptotic properties and perform simulation studies to compare our methods with the ML method. We show that the QML method provides asymptotically efficient estimation for regression parameters. Simulation studies showed that the QML and PML approaches present estimates, standard errors and coverage rates similar to the ML method. Furthermore, the second-moment assumptions required by the QML and PML methods enable us to extend the TRMs to the class of quasi-TRMs in Wedderburn's style. It allows to eliminate the non-trivial restriction on the power parameter space, and thus provides a flexible regression model to deal with continuous data. We provide an R implementation and illustrate the application of TRMs using three data sets.     

Identity Work,Techniques of Neutralization,and Deviance: Exploring the Relationship Among Older Adult Gamblers

This study investigates the value of techniques of neutralization in understanding how people involved in marginal to widely deviant behaviors perform identity work. Based on 33 in‐depth interviews with older adult gamblers, we show how techniques of neutralization are used to align personal and social identities. We describe the techniques of neutralizations our participants use along a continuum of gambling involvement, showing how techniques differ in variety and content and are contingent on larger narratives about appropriate behaviors, identities, and selves operating in contemporary society. Our research helps to refine sociologists' understandings of relationships between levels of involvement in deviant behaviors and identity work.     

Lowering Inventory Systems Costs by Using Regression-Derived Estimators of Demand Variability*

Scientific techniques for inventory management typically are applied to systems containing many items. Such techniques require an estimation of the demand variance (and mean) of each item from historical data. This research demonstrates a significant potential for improvement in system cost performance from using least-squares regression fits of a variance-to-mean functional relation instead of the standard statistical variance estimate. Even when there is a moderate degree of heterogeneity among items and when the form of the variance-to-mean relation is misspecified, substantial cost savings may be realized. The cost of statistical uncertainty may be reduced by half. The research also provides evidence that system cost is fairly insensitive to the number of items used to fit the regression. This paper provides the underlying reason why a regression-derived variance estimator yields lower cost: it is less variable than the usual individual item variance estimator.     

In Algeria: Pierre Bourdieu's photographic fieldwork

Today Pierre Bourdieu is well known as one of the most important social scientists of the 20^th century. One of the outstanding qualities of his work has been his innovative combination of different methods and research strategies as well as his analytical skills in interpreting the obtained data (his 'sociological gaze'). In this paper, we attempt to retrace the development of an extraordinary way of doing social research and show the benefit of Bourdieu's visual sociology for his empirical fieldwork and sociological theory. The article particularly stresses the significance of his photographic archive, which has long been ignored within the appreciation of Bourdieu's work. Studying Bourdieu's photography gives access to his œuvre in several new ways: not only can we understand how Bourdieu became an unconventional sociologist practicing his craft in the midst of a colonial war. Bourdieu's visual anthropology also offers an insight into the status nascendi of Bourdieu's sociology in all its elementary forms and contents. Through his photography Boudieu demonstrated the concepts of ' habitat and habitus ', the material and symbolic living conditions of the Algerian population.     

A note on pensions and firm performance: First evidence from german micro data

Using a large new data set we present results from the first econometric study of the effects of pensions on firm performance in Germany. We find evidence for positive effects on wages, reduction of labor turnover, training, and profits. We use data from the Hannover Firm Panel Study which was financially supported by the Volkswagen Foundation.     

Data availability in accounting research: Some evidence

The data availability policy of the American Accounting Association is examined to address two research questions: (1) Are data dependent results in The Accounting Review readily available for further inquiry and dissemination of accounting knowledge? (2) What are the potential factors that may account for the availability or the lack of data? Several potential factors including job rank, number of revisions before acceptance, source of data, and funding source are suggested to account for the lack of data availability. The results indicate that, in general, authors are not willing to make their data available to others. We conclude by suggesting some options that may ameliorate the situation.     

The Gamma-count distribution in the analysis of experimental underdispersed data

Event counts are response variables with non-negative integer values representing the number of times that an event occurs within a fixed domain such as a time interval, a geographical area or a cell of a contingency table. Analysis of counts by Gaussian regression models ignores the discreteness, asymmetry and heteroscedasticity and is inefficient, providing unrealistic standard errors or possibly negative predictions of the expected number of events. The Poisson regression is the standard model for count data with underlying assumptions on the generating process which may be implausible in many applications. Statisticians have long recognized the limitation of imposing equidispersion under the Poisson regression model. A typical situation is when the conditional variance exceeds the conditional mean, in which case models allowing for overdispersion are routinely used. Less reported is the case of underdispersion with fewer modeling alternatives and assessments available in the literature. One of such alternatives, the Gamma-count model, is adopted here in the analysis of an agronomic experiment designed to investigate the effect of levels of defoliation on different phenological states upon the number of cotton bolls. Data set and code for analysis are available as online supplements. Results show improvements over the Poisson model and the semi-parametric quasi-Poisson model in capturing the observed variability in the data. Estimating rather than assuming the underlying variance process leads to important insights into the process.     

Relation of Goal Setting and Goal Sharing to Performance and Conflict for Interdependent Tasks

Despite the prevalence of goal setting in organizations, researchers have not thoroughly examined the implications of goal setting to work outcomes in interdependent work settings. A field survey (n= 442) assessed the relation of goal setting and goal sharing, the extent to which others are aware of an individual's work goal, to performance and conflict across varying levels of task interdependence. The results of moderated regression analyses demonstrate that in highly interdependent tasks, the use of goal setting resulted in lower performance levels. Moreover, goal setting and goal sharing in highly interdependent tasks resulted in individuals' reporting more somatic symptoms. The results are discussed in terms of clarifying the role of goal setting for interdependent tasks.