M-quantile models with application to poverty mapping

Over the last decade there has been growing demand for estimates of population characteristics at small area level. Unfortunately, cost constraints in the design of sample surveys lead to small sample sizes within these areas and as a result direct estimation, using only the survey data, is inappropriate since it yields estimates with unacceptable levels of precision. Small area models are designed to tackle the small sample size problem. The most popular class of models for small area estimation is random effects models that include random area effects to account for between area variations. However, such models also depend on strong distributional assumptions, require a formal specification of the random part of the model and do not easily allow for outlier robust inference. An alternative approach to small area estimation that is based on the use of M-quantile models was recently proposed by Chambers and Tzavidis (Biometrika 93(2):255–268, 2006) and Tzavidis and Chambers (Robust prediction of small area means and distributions. Working paper, 2007). Unlike traditional random effects models, M-quantile models do not depend on strong distributional assumption and automatically provide outlier robust inference. In this paper we illustrate for the first time how M-quantile models can be practically employed for deriving small area estimates of poverty and inequality. The methodology we propose improves the traditional poverty mapping methods in the following ways: (a) it enables the estimation of the distribution function of the study variable within the small area of interest both under an M-quantile and a random effects model, (b) it provides analytical, instead of empirical, estimation of the mean squared error of the M-quantile small area mean estimates and (c) it employs a robust to outliers estimation method. The methodology is applied to data from the 2002 Living Standards Measurement Survey (LSMS) in Albania for estimating (a) district level estimates of the incidence of poverty in Albania, (b) district level inequality measures and (c) the distribution function of household per-capita consumption expenditure in each district. Small area estimates of poverty and inequality show that the poorest Albanian districts are in the mountainous regions (north and north east) with the wealthiest districts, which are also linked with high levels of inequality, in the coastal (south west) and southern part of country. We discuss the practical advantages of our methodology and note the consistency of our results with results from previous studies. We further demonstrate the usefulness of the M-quantile estimation framework through design-based simulations based on two realistic survey data sets containing small area information and show that the M-quantile approach may be preferable when the aim is to estimate the small area distribution function.     

An Integrated Approach to Select Key Quality Indicators in Transit Services

Social Indicators Research - Recent interests in transit services have captured attention of experts on the monitoring of public transport quality. Previous research focused on relevant models and...     

DOING THERAPY: A POST-STRUCTURAL RE-VISION*

The purpose of this essay is to develop a way to look at doing therapy based on (a) Wittgenstein's concept of “language game”; (b) the relationship between Wittgenstein's “private language” argument, language games, and constructivism; and (c) post-structural thinking about language, how therapy works within language, and how language works within therapy. Case material is used to illustrate the usefulness of this approach.     

THE MULTIPLE BODIES OF THE MEDICAL RECORD:

This article argues that the medical record is an important focus for sociological research. In medical work, the modern patient's body that Foucault has so aptly described is produced through embodied, materially heterogeneous work, and the medical record plays a crucial role in this production. It does not simply represent this body's history and geography; it is a central element in the material rewriting of these. Simultaneously, the record fulfills a core role in the production of a body politic . As the record is involved in the performance of the patient's body, it is also involved in the performance of the clinic in which that body comes to life. Finally, we argue that different records and different practices of reading and writing are intertwined with the production of different patient's bodies, bodies politic, and bodies of knowledge. As organizational infrastructure, the medical record affords the interplay and coordination of divergent worlds. Seen as a site where multiple stories about patients and organizations are at stake, including the interoperability between these stories, the medical record becomes highly relevant both analytically and politically.     

Maximum likelihood estimation of correlation between maximal oxygen consumption and the 6-min walk test in patients with chronic heart failure

Maximal oxygen consumption (VO₂max) is the standard measurement used to quantify cardiovascular functional capacity and aerobic fitness. Unfortunately, it is a costly, impractical and labour-intensive measure to obtain. The 6-min walk test (6MWT) also assesses cardiopulmonary function, but in contrast to the VO₂max test, it is inexpensive and can be performed almost anywhere. Various medical studies have addressed the correlation between VO₂max and 6MWT in patients with chronic heart failure. Of particular interest, from a medical point of view, is the conditional correlation between the two measures given the individual's height, weight, age and gender. In this paper, we have calculated the maximum likelihood estimate of the conditional correlation in patients with chronic heart failure under the assumption of skew normality. Data were recorded from 98 patients in the Operative Unit of Thoracic Surgery in Bari, Italy. The estimated conditional correlation was found to be much smaller than estimated marginal correlations reported in the medical literature.     

A Critical Discussion and Practical Recommendations on Some Issues Relevant to the Nonprobabilistic Treatment of Uncertainty in Engineering Risk Assessment

Models for the assessment of the risk of complex engineering systems are affected by uncertainties due to the randomness of several phenomena involved and the incomplete knowledge about some of the characteristics of the system. The objective of this article is to provide operative guidelines to handle some conceptual and technical issues related to the treatment of uncertainty in risk assessment for engineering practice. In particular, the following issues are addressed: (1) quantitative modeling and representation of uncertainty coherently with the information available on the system of interest; (2) propagation of the uncertainty from the input(s) to the output(s) of the system model; (3) (Bayesian) updating as new information on the system becomes available; and (4) modeling and representation of dependences among the input variables and parameters of the system model. Different approaches and methods are recommended for efficiently tackling each of issues (1)?(4) above; the tools considered are derived from both classical probability theory as well as alternative, nonfully probabilistic uncertainty representation frameworks (e.g., possibility theory). The recommendations drawn are supported by the results obtained in illustrative applications of literature.     

RACE,CLASS, GENDER,AND SOCIAL SPACE: Using an Intersectional Approach to Study Immigration Attitudes

This study uses an intersectional approach to predict attitudes toward immigrants by examining the intersections of race, class, gender, and social space. With data from the 2004 General Social Survey and the 2000 Census, generalized hierarchal linear modeling generates significant two‐way and three‐way interactions in predicting attitudes toward immigrants taking jobs, improving the economy, committing crime, and migrating to the United States. Important differences in attitudes between groups and within groups only emerge when particular intersections are considered in the analysis. One implication is that pro‐immigrant organizations may gain greater support by devising political strategies from an intersectional perspective.     

Clustering via nonparametric density estimation

Although Hartigan (1975) had already put forward the idea of connecting identification of subpopulations with regions with high density of the underlying probability distribution, the actual development of methods for cluster analysis has largely shifted towards other directions, for computational convenience. Current computational resources allow us to reconsider this formulation and to develop clustering techniques directly in order to identify local modes of the density. Given a set of observations, a nonparametric estimate of the underlying density function is constructed, and subsets of points with high density are formed through suitable manipulation of the associated Delaunay triangulation. The method is illustrated with some numerical examples.     

A longitudinal study of the effects of charismatic leadership and organizational culture on objective and perceived corporate performance

We investigated the combined effects of charismatic leadership and organizational culture on perceived and objective company performance using a longitudinal design. Employees (N = 1214) in 46 branches of a large Dutch bank rated branch management on charismatic leadership, organizational culture in terms of work practices, as well as perceived organizational performance. Objective performance data were collected twice, two years apart. The split sample technique attenuated common source bias. Results of structural equation modeling, in which Time 1 financial performance measures were controlled, revealed that charisma increased financial performance; however culture did not do so. Culture and charisma were significantly related to perceived performance, and culture and charisma were interrelated. A longer time interval may be necessary before the effects of culture on financial performance become apparent. The findings are discussed against the backdrop of the value of intangible resources.