Asymptotic properties of a quast-maximum likelihood estimator in truncated regression model with serial correlation

Robinson (1982a) presented a general approach to serial correlation in limited dependent variable models and proved the strong consistency and asymptotic normality of the quasi-maximum likelihood estimator (QMLE) for the Tobit model with serial correlation, obtained under the assumption of independent errors. This paper proves the strong consistency and asymptotic normality of the QMLE based on independent errors for the truncated regression model with serial correlation and gives consistent estimators for the limiting covariance matrix of the QMLE.     

Stochastic simulation based genetic algorithm for chance constrained data envelopment analysis problems

Genetic algorithm (GA) approach is developed for solving the P-model of chance constrained data envelopment analysis (CCDEA) problems, which include the concept of “Satisficing”. Problems here include cases in which inputs and outputs are stochastic, as well as cases in which only the outputs are stochastic. The basic solution technique for the above has so far been deriving “deterministic equivalents”, which is difficult for all stochastic parameters as there are no compact methods available. In the proposed approach, the stochastic objective function and chance constraints are directly used within the genetic process. The feasibility of chance constraints are checked by stochastic simulation techniques. A case of Indian banking sector has been presented to illustrate the above approach.     

The Panchshil Buddha Vihar Group: Dalit migrant life and group solidarity during the pandemic

ABSTRACT

This narrative is based on my previous experience and telephonic discussions with Dalit (Dalits are an ex-untouchable caste of India, who have been subject to discrimination and exclusion historically and placed at the bottom on the Indian social system) migrants during the COVID-19 pandemic. The narrative aims to highlight the life and trajectory of Dalit migrants pre- and during the pandemic. In addition, the narrative illustrates their everyday strategy as a group in response to the pandemic. Further, the narrative describes various means and methods of Dalit migrants to advance community solidarity, which has helped them to survive and escape the city, to return to their villages.     

Integrated approach for optimizing quality control in international manufacturing networks

Abstract

This article aims at providing an integrated approach for optimizing quality control in International Manufacturing Networks (IMN) which can be characterized by consisting of numerous plants acting autonomously according to an individual target system. A key challenge is to ensure the overall process quality despite distributed value creation processes and differing target systems in dynamic environments. Hence, the developed approach allows for identifying potentials in the quality control strategy using a value stream-based method to visualize quality characteristics and procedures in the production process chain. Furthermore, the approach contains a framework for identifying possible improvement measures and a simulation-based evaluation concept to evaluate the effects of different measures with respect to individual target systems. The simulation combines elements of a discrete-event simulation in order to depict the value stream with agent-based modelling for realizing different target systems by considering distinctive plant roles. The article concludes with a case study of a globally operating automotive supplier to apply the approach. A forward research agenda is proposed that evaluates the approach in multiple cases, deriving patters across companies or industries.     

Integrating sustainable supply chain practices with operational performance: an exploratory study of Chinese SMEs

Abstract

With growing regulatory and market pressure to implement green practices, SMEs are facing enormous challenges to simultaneously improve operational and green performances of their supply chains. The paper aims to understand the green practices adopted by Chinese SMEs in the packaging sector in order to assess the impact of these practices in improving the operational performance. Case study-based research methodology is adopted and semi-structured interviews are conducted to collect data from seven SMEs in this study. Both in-case and cross-case analyses are performed to understand the green practices being adopted with the focus on improving the operational performance. The findings of this study indicate that although most SMEs understand the importance of green practices, they have limited knowledge to integrate these practices to improve operational performance. Integration and alignment of green activities with the operational improvement measures are identified as critical factors to develop an efficient green supply chain.     

Synergies and misalignments in lean and green practices: a logistics industry perspective

Abstract

This paper conducts an exploratory case study-based research in three companies to identify the main synergies and misalignments between Lean and Green in the context of a range of distribution networks operating globally, regionally and domestically. The research strategy applied by this study is exploratory multiple case studies in three companies, particularly in the road transport and logistics sector. Semi-structured interviews with 15 executives from three companies were conducted to identify activities within logistics operations leading to synergies and misalignment between Lean and Green practices. The outcome of the three cases shows that several improvements can be achieved by the simultaneous adoption of Lean and Green. The study contributes to the literature by extending the research in the logistics sector and providing examples from a wide variety of logistics operations on synergies and misalignments between Lean and Green practices. The findings and outcome of this study are a starting point for further research in the logistics sector.     

Estimation of mean in presence of non-response using two phase sampling scheme

This paper considers the problem of estimating the population mean using information on an auxiliary variable in presence of non-response. Some modified ratio, product and regression estimators in double sampling have been suggested and their properties are studied. It is shown that to the first degree of approximation, estimators based on estimated optimum values have the same variance as that of the optimum estimators. An empirical study is carried to judge the merits of the suggested estimators over conventional unbiased estimator and other known estimators. Both theoretical and empirical study results present the soundness and usefulness of the suggested estimators in practice.     

Efficient Block Designs for Dependent Observations—A Computer-Aided Search

In this article, the exchange and interchange algorithm of Zergaw (1989 Zergaw , G. ( 1989 ). A sequential method of constructing optimal block designs . Austral. J. Statist. 31 : 333 – 342 .[Crossref] , [Google Scholar]) and Martin and Eccleston (1992 Martin , R. J. , Eccleston , J. A. ( 1992 ). Recursive formulae for constructing block designs with dependent errors . Biometrika 79 : 426 – 430 .[Crossref], [Web of Science ®] , [Google Scholar]) have been modified and used for searching efficient block designs for making all possible pairwise treatment comparisons when observations are dependent. The lower bounds to the A- and D-efficiencies of the designs in a given class of the designs have been obtained for correlated observation structure and the procedure of computing lower bounds to A- and D-efficiencies has been incorporated in the algorithm. The algorithm has been translated into a computer program using Microsoft Visual C++. Using this program, a search for efficient designs for making all possible pairwise treatment comparisons has been made for v ≤ 10, b ≤ 33, k ≤ 10 such that bk ≤ 100 and v > k. The block designs considered are usual block designs (rectangular block designs) and circular block designs. Nearest neighbor (NN), autoregressive of order 1 (AR(1)) correlation structures are studied. The ranges of correlation coefficients for different correlation structures investigated are |ρ|≤0.50 for NN correlation structure in rectangular blocks, |ρ|≤0.45 for NN correlation structure in circular blocks, and |ρ|≤0.95 for AR(1) correlation structure. For these ranges, the matrix of correlation coefficients among observations within a block is positive definite. Robustness aspects of designs that are efficient for a given value of correlation have been investigated against other values of correlation coefficients. Robustness aspects of designs that are efficient for independent observations have also been studied for experimental situations with dependent observations.