A novel weighted likelihood estimation with empirical Bayes flavor

We propose a novel approach to estimation, where a set of estimators of a parameter is combined into a weighted average to produce the final estimator. The weights are chosen to be proportional to the likelihood evaluated at the estimators. We investigate the method for a set of estimators obtained by using the maximum likelihood principle applied to each individual observation. The method can be viewed as a Bayesian approach with a data-driven prior distribution. We provide several examples illustrating the new method and argue for its consistency, asymptotic normality, and efficiency. We also conduct simulation studies to assess the performance of the estimators. This straightforward methodology produces consistent estimators comparable with those obtained by the maximum likelihood method. The method also approximates the distribution of the estimator through the “posterior” distribution.     

Lead time adjustment through scrap management

In a discrete parts manufacturing environment, it is necessary to compensate for the decreasing planned batch size resulting from production of scrap (defectives) in the production line, by increasing the planned production volume. This calls for a revision in the initially computed manufacturing lead time (MLT). A survey of the literature reveals that although issues related to product quantity regeneration have been studied in detail, little has been done to assess the impact on manufacturing lead times. This paper discusses the impact of scrap on manufacturing lead time in a shop with an intermittent-flow, bath-oriented, discrete-parts manufacturing environment, producing make-to-stock items.     

Geriatric Care during Public Health Emergencies: Lessons Learned from Novel Corona Virus Disease (COVID-19) Pandemic

ABSTRACT

Geriatric care in public health emergencies is a serious concern, while, high case-fatalities among older adults across the globe in COVID-19 pandemic implies lack of preparedness. Most of the countries irrespective of developing and developed one enormously struggling because of an inchoate response system ignorant of geriatric health needs. Therefore, a robust approach is highly essential that requires an integrated emergency preparedness by addressing geriatric care.     

Comments on ‘Application of an adaptive design to a randomized phase II selection trial in gastric cancer: a report of the study design’ by Satoshi Morita and Junichi Sakamoto. Pharmaceutical Statistics

In this commentary, we show that the treatment selection probabilities in Morita and Sakamoto [1] could be different if safety information is considered. Copyright © 2012 John Wiley & Sons, Ltd.     

Evaluating Quality of Life in Urban Areas (Case Study: Noorabad City, Iran)

Quality of urban life (QOUL) has become an important field within urban studies. The increased level of attention to this topic is due to the increasing importance of QoL studies in monitoring public policies and in the role they can play as effective tools in urban management and planning. The main objective of this study is to measure the QOUL in the town of Noorabad in Iran, using subjective and objective indicators. In addition to secondary datasets, this study relies on a perception survey of households in the selected city. Based on an 11-point Likert scale, the mean of the overall life satisfaction of the respondents was found to be 6.06. At the same time, it has been found that satisfaction from employment opportunities is lowest among all other indicators. The comparison between the subjective and objective QoL in Noorabad indicated that 25 % of the households are in a state of well-being, 30.1 % are in a state of deprivation, while 24.4 % are in dissonance and 20.4 % are in a state of adaptation. Although correlation between objective and subjective dimensions of the QoL has not been found to be high, in general, the findings of this study reveal the importance of simultaneous studying of both objective and subjective dimensions of QoL. Results and findings of this study will be useful in designing and implementing future policies in the town of Noorabad.     

SHRINKAGE, PRETEST AND ABSOLUTE PENALTY ESTIMATORS IN PARTIALLY LINEAR MODELS

We consider a partially linear model in which the vector of coefficients β in the linear part can be partitioned as ( β ₁, β ₂) , where β ₁ is the coefficient vector for main effects (e.g. treatment effect, genetic effects) and β ₂ is a vector for ‘nuisance’ effects (e.g. age, laboratory). In this situation, inference about β ₁ may benefit from moving the least squares estimate for the full model in the direction of the least squares estimate without the nuisance variables (Steinian shrinkage), or from dropping the nuisance variables if there is evidence that they do not provide useful information (pretesting). We investigate the asymptotic properties of Stein‐type and pretest semiparametric estimators under quadratic loss and show that, under general conditions, a Stein‐type semiparametric estimator improves on the full model conventional semiparametric least squares estimator. The relative performance of the estimators is examined using asymptotic analysis of quadratic risk functions and it is found that the Stein‐type estimator outperforms the full model estimator uniformly. By contrast, the pretest estimator dominates the least squares estimator only in a small part of the parameter space, which is consistent with the theory. We also consider an absolute penalty‐type estimator for partially linear models and give a Monte Carlo simulation comparison of shrinkage, pretest and the absolute penalty‐type estimators. The comparison shows that the shrinkage method performs better than the absolute penalty‐type estimation method when the dimension of the β ₂ parameter space is large.     

Development NGOs and Political Participation of the Poor in Bangladesh and Nepal

This paper examines the role of development NGOs (nongovernmental organizations) in furthering the political participation of the poor, with data from Bangladesh and Nepal. The topic is discussed from three aspects: the role of NGOs in prodemocracy movements, the issues raised by antiglobalization movements, and the extent of NGO involvement in local government elections. The paper draws on fieldwork conducted in two villages—one in Bangladesh and the other in Nepal. It is concluded that development NGOs tend to contribute more to elite interests than to the democratic political participation of the poor.     

An Improved Method on Wilcoxon Rank Sum Test for Gene Selection from Microarray Experiments

Selecting a small subset out of the thousands of genes in microarray data is important for accurate classification of phenotypes. In this paper, we propose a flexible rank-based nonparametric procedure for gene selection from microarray data. In the method we propose a statistic for testing whether area under receiver operating characteristic curve (AUC) for each gene is equal to 0.5 allowing different variance for each gene. The contribution to this “single gene” statistic is the studentization of the empirical AUC, which takes into account the variances associated with each gene in the experiment. Delong et al. proposed a nonparametric procedure for calculating a consistent variance estimator of the AUC. We use their variance estimation technique to get a test statistic, and we focus on the primary step in the gene selection process, namely, the ranking of genes with respect to a statistical measure of differential expression. Two real datasets are analyzed to illustrate the methods and a simulation study is carried out to assess the relative performance of different statistical gene ranking measures. The work includes how to use the variance information to produce a list of significant targets and assess differential gene expressions under two conditions. The proposed method does not involve complicated formulas and does not require advanced programming skills. We conclude that the proposed methods offer useful analytical tools for identifying differentially expressed genes for further biological and clinical analysis.