Sensitivity analysis of the unconfoundedness assumption with an application to an evaluation of college choice effects on earnings

We evaluate the effects of college choice on earnings using Swedish register databases. This case study is used to motivate the introduction of a novel procedure to analyse the sensitivity of such an observational study to the assumption made that there are no unobserved confounders – variables affecting both college choice and earnings. This assumption is not testable without further information, and should be considered an approximation of reality. To perform a sensitivity analysis, we measure the departure from the unconfoundedness assumption with the correlation between college choice and earnings when conditioning on observed covariates. The use of a correlation as a measure of dependence allows us to propose a standardised procedure by advocating the use of a fixed value for the correlation, typically 1% or 5%, when checking the sensitivity of an evaluation study. A correlation coefficient is, moreover, intuitive to most empirical scientists, which makes the results of our sensitivity analysis easier to communicate than those of previously proposed methods. In our evaluation of the effects of college choice on earnings, the significantly positive effect obtained could not be questioned by a sensitivity analysis allowing for unobserved confounders inducing at most 5% correlation between college choice and earnings.     

Generalized Linear Factor Models: A New Local EM Estimation Algorithm

In this article, a general approach to latent variable models based on an underlying generalized linear model (GLM) with factor analysis observation process is introduced. We call these models Generalized Linear Factor Models (GLFM). The observations are produced from a general model framework that involves observed and latent variables that are assumed to be distributed in the exponential family. More specifically, we concentrate on situations where the observed variables are both discretely measured (e.g., binomial, Poisson) and continuously distributed (e.g., gamma). The common latent factors are assumed to be independent with a standard multivariate normal distribution. Practical details of training such models with a new local expectation-maximization (EM) algorithm, which can be considered as a generalized EM-type algorithm, are also discussed. In conjunction with an approximated version of the Fisher score algorithm (FSA), we show how to calculate maximum likelihood estimates of the model parameters, and to yield inferences about the unobservable path of the common factors. The methodology is illustrated by an extensive Monte Carlo simulation study and the results show promising performance.     

Experimentation order in factorial designs: new findings

Under some very reasonable hypotheses, it becomes evident that randomizing the run order of a factorial experiment does not always neutralize the effect of undesirable factors. Yet, these factors do have an influence on the response, depending on the order in which the experiments are conducted. On the other hand, changing the factor levels is many times costly; therefore it is not reasonable to leave to chance the number of changes necessary. For this reason, run orders that offer the minimum number of factor level changes and at the same time minimize the possible influence of undesirable factors on the experimentation have been sought. Sequences which are known to produce the desired properties in designs with 8 and 16 experiments can be found in the literature. In this paper, we provide the best possible sequences for designs with 32 experiments, as well as sequences that offer excellent properties for designs with 64 and 128 experiments. The method used to find them is based on a mixture of algorithmic searches and an augmentation of smaller designs.     

Culture loss: American Indian family disruption, urbanization, and the Indian Child Welfare Act

This study examined the perceptions and views of urban American Indian parents regarding foster care and American Indian family issues. Findings highlight four themes: (1) discouragement from working with the current foster care system, (2) the role of culture in caregiving, (3) differing definitions of family and relatedness, and (4) the effects of historical pain due to past family disruption. These themes are used to formulate guidelines for the development of an American Indian foster care and child welfare program.     

Measuring management quality in the factory

The last decade has seen a growing consensus that manufacturing matters. The factory as the producing unit is the core of the firm's manufacturing activities. However, even now, it is not agreed on or even fully understood what constitutes a well-managed factory. This article attempts to create a causal model of management quality in the plant, identifying key managerial levers for improving plant performance. The model is based on an integrated view of three core processes: supply chain, product and process development, and strategy deployment. We postulate that the joint performance of the three processes is determined by the quality with which they are managed. Management quality is operationalized as consisting of six types of action: delegation (or decentralization), integration (or coordination), measurement, employee participation, communication, and employee development.This management quality model has been applied to the design of the Top Usine 1995 Best Factory Award administered in cooperation with the French weekly L'Usine Nouvelle. Data collected from participating plants do substantiate our view that plant performance is substantially driven by management quality: the six management quality dimensions are shown to be statistically linked to performance improvement rates in the plant, and we provide further evidence of this link by detailing the case example of the award winner. Our survey also shows that supply management appears to be a common problem area for the factories participating in the Top Usine award, including the best ones.     

The Chinese and Indian Automobile Industry in Perspective: Technology Appropriation, Catching-up and Development

The comparison of the automobile industry in China and India allows us to shed light on the economic processes of emergence at large. There is a stark contrast in the capacities of autonomisation and endogenisation of the sector in the two countries. This contrast serves as an analyser of the relationships between the modes of sector opening and the paths of technological catching-up that is at the core of the phenomenon of emergence.

Comparison of normal probability plots and dot plots in judging the significance of effects in two level factorial designs

In this article, we present a study carried out to compare the effectiveness of the normal probability plot (NPP) and a simple dot plot in assessing the significance of the effects in experimental designs with factors at two levels (2 ^k?p designs). Several groups of students who had just completed a course that covered factorial designs were asked to identify the significant effects in a total of 32 situations, 16 of which were represented using NPPs and the other 16 using dot plots. Although the 32 scenarios were said to be different, there were really only 16 different situations, each of which was represented using the two methods to be compared. A simple graphical analysis shows no evidence that there is a difference between the two procedures. However, in designs with 16 runs there are some cases where NPP seems to give slightly better results.     

Review of practices for keeping people with disabilities in employment: moving beyond the concept of compensation to implement a developmental approach

In France, there are strict laws in place to ensure that people with disabilities have access to, and can remain in employment. In this context, many businesses have "group agreements", to support and fund in-house actions in this area. For the last five years, as part of our work as consultant ergonomists, we have carried out over fifty ergonomics interventions for one of our clients to adapt the working environment for persons with disabilities. This paper presents an analysis of our practices to adapt working environment for employees with disabilities by means of a review of these different interventions. This analysis of practices specifically focuses on an issue we consider to be of vital importance: how to get past the concept of an impairment which can be compensated for with technical solutions, a concept in which both French legislation, and the practices of certain professionals working in the field of occupational disability are firmly rooted, and move towards a developmental approach, with the aim of designing an "enabling environment" [2-4,13].