Distribution-Free Exceedance CUSUM Control Charts for Location

Distribution-free (nonparametric) control charts can be useful to the quality practitioner when the underlying distribution is not known. A Phase II nonparametric cumulative sum (CUSUM) chart based on the exceedance statistics, called the exceedance CUSUM chart, is proposed here for detecting a shift in the unknown location parameter of a continuous distribution. The exceedance statistics can be more efficient than rank-based methods when the underlying distribution is heavy-tailed and/or right-skewed, which may be the case in some applications, particularly with certain lifetime data. Moreover, exceedance statistics can save testing time and resources as they can be applied as soon as a certain order statistic of the reference sample is available. Guidelines and recommendations are provided for the chart's design parameters along with an illustrative example. The in- and out-of-control performances of the chart are studied through extensive simulations on the basis of the average run-length (ARL), the standard deviation of run-length (SDRL), the median run-length (MDRL), and some percentiles of run-length. Further, a comparison with a number of existing control charts, including the parametric CUSUM chart and a recent nonparametric CUSUM chart based on the Wilcoxon rank-sum statistic, called the rank-sum CUSUM chart, is made. It is seen that the exceedance CUSUM chart performs well in many cases and thus can be a useful alternative chart in practice. A summary and some concluding remarks are given.     

On estimation of the PDF and CDF of the Lindley distribution

This article addresses two methods of estimation of the probability density function (PDF) and cumulative distribution function (CDF) for the Lindley distribution. Following estimation methods are considered: uniformly minimum variance unbiased estimator (UMVUE) and maximum likelihood estimator (MLE). Since the Lindley distribution is more flexible than the exponential distribution, the same estimators have been found out for the exponential distribution and compared. Monte Carlo simulations and a real data analysis are performed to compare the performances of the proposed methods of estimation.     

Exact estimation of multiple directed acyclic graphs

This paper considers structure learning for multiple related directed acyclic graph (DAG) models. Building on recent developments in exact estimation of DAGs using integer linear programming (ILP), we present an ILP approach for joint estimation over multiple DAGs. Unlike previous work, we do not require that the vertices in each DAG share a common ordering. Furthermore, we allow for (potentially unknown) dependency structure between the DAGs. Results are presented on both simulated data and fMRI data obtained from multiple subjects.     

That’s the ticket: explicit lottery randomisation and learning in Tullock contests

Theory and Decision - Most laboratory experiments studying Tullock contest games find that bids significantly exceed the risk-neutral equilibrium predictions. We test the generalisability of these...     

THE GHETTO FABULOUS AESTHETIC IN CONTEMPORARY BLACK CULTURE

With diamonds, mink, and champagne, black popular culture has, in recent years, made an audacious spectacle of conspicuous commodity consumption. Commonly termed ‘bling’, the ‘ghetto fabulous’ aesthetic of these flashy displays has prompted vociferous debate about the cultural meanings of contemporary black consumerism. Is it pathological? Subversive? Deviant? Since the nineties when it first appeared, the ghetto fabulous aesthetic has left its mark on a range of cultural productions from music videos to ghetto lit, fashion to film, walking a familiar line from defiance to bowdlerization, from raucous wild child of the streets to co-opted product tagline.

This essay explores a new cinematic genre within this repertoire, the ghetto fabulous genre of black film that has emerged to variously castigate and congratulate black investments in ghetto fabulous bling. Appearing at the close of the twentieth century, the genre reflects key shifts in the political imaginary and economic transformations of the ‘post-soul’ era. Drawing on two such texts, Barbershop (Tim Story 2002) and Barbershop 2: Back In Business (Kevin Rodney Sullivan 2004), studio films with all-black casts and directed by young African-American filmmakers, this analysis focuses on their engagement with contemporary cultural tensions over class and consumerism, their narrative containment of a transformative black politics, and their reconciliation of post-soul priorities with hegemonic discourses of the market. I argue that ghetto fabulous films are quintessential products of the post-soul era, their allegorical priorities in pointed accord with neo-liberal individualism and the promise of class transcendence. Performing crucial work of hegemonic cooptation, these texts offer archetypes of the ghetto entrepreneur and black enterprise itself as a salvational sphere for the urban poor. Reining in unruly desires, these texts draw working-class African Americans into the capitalist fold, articulating a post-soul politics that preaches black acquiescence with hegemonic discourses of advanced capitalism.     

Generalized median graphs and applications

We study the so-called Generalized Median graph problem where the task is to construct a prototype (i.e., a ‘model’) from an input set of graphs. While our primary motivation comes from an important biological imaging application, the problem effectively captures many vision (e.g., object recognition) and learning problems, where graphs are increasingly being adopted as a powerful representation tool. Existing techniques for his problem are evolutionary search based; in this paper, we propose a polynomial time algorithm based on a linear programming formulation. We propose an additional algorithm based on a bi-level method to obtain solutions arbitrarily close to the optimal in (worst case) non-polynomial time. Within this new framework, one can optimize edit distance functions that capture similarity by considering vertex labels as well as he graph structure simultaneously. We first discuss experimental evaluations in context of molecular image analysis problems—he methods will provide the basis for building a topological map of all 23 pairs of the human chromosome. Later, we include (a) applications to other biomedical problems and (b) evaluations on a public pattern recognition graph database. This work was supported by NSF grants CCF-0546509, IIS-0713489, and NIH grant GM 072131-23. The second author was also supported in part by the Department of Biostatistics and Medical Informatics, UW-Madison and UW ICTR, funded through an NIH Clinical and Translational Science Award (CTSA), grant number 1 UL1 RR025011.     

A NOTE ON SAMPLING DESIGNS FOR RANDOM PROCESSES WITH NO QUADRATIC MEAN DERIVATIVE

Several authors have previously discussed the problem of obtaining asymptotically optimal design sequences for estimating the path of a stochastic process using intricate analytical techniques. In this note, an alternative treatment is provided for obtaining asymptotically optimal sampling designs for estimating the path of a second order stochastic process with known covariance function. A simple estimator is proposed which is asymptotically equivalent to the full‐fledged best linear unbiased estimator and the entire asymptotics are carried out through studying this estimator. The current approach lends an intuitive statistical perspective to the entire estimation problem.     

Background and Adjustment Capacity of Sexually Abused Girls and their Perceptions of Intervention

The main objective of the study was to understand the adjustment capacity of sexually abused girls in the age group 13–18 years in Kolkata, India. The study also attempted to understand how the sexually abused girls perceived the psychological interventions, i.e. individual and group counselling, which they had received. A group of 120 sexually abused Indian girls and 120 non‐sexually abused Indian schoolgirls residing in Kolkata Metropolitan City and its suburbs were studied. Findings revealed that the majority of the sexually abused girls came from nuclear and poor families (93.3%) with a low educational background. More than two‐thirds (73.3%) were lured with promises of job prospects, marriage and a better life and then abused sexually. Emotional and social adjustment capacity of sexually abused and non‐sexually abused girls differed significantly (p < 0.05). Overall, the perception of more than two‐thirds of the sexually abused girls of the rehabilitation homes they lived in was found to be positive. Further, the girls who reported they gained considerably from counselling had a better adjustment capacity compared to those who reported they did not benefit from counselling. Copyright © 2011 John Wiley & Sons, Ltd.     

Nonparametric Phase-II monitoring for detecting monotone trend based on inverse sampling

Recently, Mukherjee and Bandyopadhyay (J Stat Plan Inference, 2011, doi:10.1016/j.jspi.2011.02.017) introduced some partially sequential tests for detecting liner trend among the incoming series of observations when a training sample is available a-priori. Their work is very useful in econometric or environmental monitoring under certain situations. The present work is intended for generalization of their tests for any monotone trend. We develop two nonparametric tests for the identity of some unknown univariate continuous distribution functions against monotone or unidirectional trend in location. One of these two tests is based on usual ranks and the other is based on sequential ranks. These are typical nonparametric tests for monitoring structural changes. Performance of the two tests are compared using asymptotic studies as well as through some numerical results based on Monte-Carlo simulations. An illustration is offered using a real data on monthly production of certain beverage.