A unified framework for analysis and comparison of randomized response surveys of binary characteristics

The randomized response (RR) procedures for estimating the proportion (π)$(\pi )$ of a population belonging to a sensitive or stigmatized group ask each respondent to report a response by randomly transforming his/her true attribute into one of several response categories. In this paper, we present a common framework for discussing various RR surveys of dichotomous populations with polychotomous responses. The unified approach is focused on the substantive issues relating to respondents’ privacy and statistical efficiency and is helpful for fair comparison of various procedures. We describe a general technique for constructing unbiased estimators of π$\pi$ based on arbitrary RR procedures, from unbiased estimators based on an open survey with the same sampling design. The technique works well for any sampling design p(s)$p(s)$ and also for variance estimation. We develop an approach for comparing RR procedures, taking both respondents’ protection and statistical efficiency into account. For any given RR procedure with three or more response categories, we present a method for designing an RR procedure with a binary response variable which provides the same respondents’ protection and at least as much statistical information. This result suggests that RR surveys of dichotomous populations should use only binary response variables.     

The concept of risk unbiasedness in statistical prediction

This paper extends the concept of risk unbiasedness for applying to statistical prediction and nonstandard inference problems, by formalizing the idea that a risk unbiased predictor should be at least as close to the “true” predictant as to any “wrong” predictant, on the average. A novel aspect of our approach is measuring closeness between a predicted value and the predictant by a regret function, derived suitably from the given loss function. The general concept is more relevant than mean unbiasedness, especially for asymmetric loss functions. For squared error loss, we present a method for deriving best (minimum risk) risk unbiased predictors when the regression function is linear in a function of the parameters. We derive a Rao–Blackwell type result for a class of loss functions that includes squared error and LINEX losses as special cases. For location-scale families, we prove that if a unique best risk unbiased predictor exists, then it is equivariant. The concepts and results are illustrated with several examples. One interesting finding is that in some problems a best unbiased predictor does not exist, but a best risk unbiased predictor can be obtained. Thus, risk unbiasedness can be a useful tool for selecting a predictor.     

Comparison of estimators of a dispersion matrix under generalized pitman nearness criterion

Some equivariant estimators of the dispersion matrix of a multivariate normal population are compared using the generalized Pitman nearness criterion based on the entropy loss function. It is shown that, under the group of lower triangular transformations, a best equivariant estimator does not exist. Existence of best estimators in certain subclasses are discussed and the performances of two commonly used estimators are compared. Some properties of central chi-square distributions are obtained and used to derive the main results.     

Epilepsy in older women

Women suffering from epilepsy require special attention throughout their life. In this review, management of epilepsy during the periods of perimenopause, menopause and late maturity is discussed. The effect of epilepsy on age at menopause, changes in seizure frequency during perimenopause and menopause, and the risks of hormone replacement therapy are also presented. Altered antiepileptic drug pharmacokinetics with increasing age and the management of this vulnerable population is also discussed.     

Stochastic comparisons of multivariate frailty models

A multivariate frailty model in which survival function depends on baseline distributions of components and the frailty random variable is considered. Since misspecification in choice of frailty distribution and/or baseline distribution may affect the distribution of multivariate frailty model, using theory of stochastic orders, we compare multivariate frailty models arising from different choices of frailty distribution.     

A Development Delivery Institution for the Tribal Communities: Experience of the National Rural Employment Guarantee Scheme in India

This article examines the varied impacts of the National Rural Employment Guarantee Scheme (NREGS) as a development delivery institution for the tribal communities vis‐à‐vis other social groups across the Indian States, using the framework of new institutional economics. A number of State‐specific, socio‐economic institutional factors seem to be responsible for these variations. The article therefore suggests institutional reforms and convergence of the development initiatives of the Ministry of Tribal Affairs with the NREGS in order to realise the optimal potential of the scheme, and, in particular, to ensure greater livelihood opportunities for these marginalised groups and their entitlement to productive resources with greater socio‐economic and political empowerment.     

Application of value stream mapping (VSM) for lean and cycle time reduction in complex production environments: a case study

The application of VSM is a proven approach for lean-based improvements. Typically, this becomes challenging, when applied for complex production environments. The purpose of this research is to demonstrate, how with some approximations and simplifications in VSM application, lean can be successfully achieved in these environments. The research follows case study method and systematically guides about the segregation and treatment of non-value-adding(NVA) and value-adding (VA) activities of heavy-duty industrial power transformer making process. The focal company operates in engineer to order (ETO) and high-mix low-volume (HMLV) environments. With a research team using gemba walks and systematic questioning technique, relevant data were collected for mapping. Taguchi method was also applied for one of the critical steps, which was influencing cycle time and energy requirements. The generalisable findings endorse the strengths of approach for lean by addressing wastes and cycle time reduction. The study establishes that VSM application-based lean messages remain same for both simple and complex environments. It also exposes that non-compliance of ‘VSM assumptions’ and ‘micro-concepts’ are the root causes for application complexities. The study also offers useful insights and practical guidelines to facilitate lean in ETO, construction and HMLV production environments.