Local principal differential analysis: Graphical methods for functional data with covariates

We focus on principal differential analysis (PDA) of functional data for obtaining a low-dimensional representation of a collection of curves. PDA assumes there exists a linear differential operator that results in the zero-function when it is applied to each of the data curves, or equivalently, that the curves belong to a low-dimensional subspace of a normed linear space. PDA sets out to estimate this linear differential operator from the data and proceeds from there. Our contribution is to explain how subject covariates can be incorporated into a PDA analysis for graphical exploration of patterns in the data.     

DOES THE WOMEN,INFANTS, AND CHILDREN PROGRAM IMPROVE INFANT HEALTH OUTCOMES?

We reevaluate the causal impacts of prenatal participation in the Women, Infants, and Children (WIC) supplemental nutrition program on birth outcomes by simultaneously accounting for self-selection into WIC and systematic underreporting of program participation. Combining survey data from the Early Childhood Longitudinal Study-Birth Cohort with administrative data from the USDA, we extend partial identification methods to reflect institutional details of the WIC program and validate WIC program participation for a mixture of positive and negative responses. Our preferred estimates imply that WIC increases the prevalence of normal birth weight by at least 4.8% and normal gestation duration by at least 3.7%. (JEL C14, C21, I12, I31, I38)     

Groom price-female human capital: Some empirical evidence

This paper examines the effect of female human capital endowment on the groom price or dowry by using a newly available data set that was created by surveying the middle-class residents of Patna, Bihar. The estimates based on the OLS and 2SLS suggest the existence of positive association between the two variables for the sample under study. The result can be viewed as a positive; albeit, a small step towards settling the issue as to whether or not dowry is an obstacle to female human capital formation.     

Ergonomic intervention in aonla pricking operation during preserve preparation in food processing industries

Aonla is an important Indian fruit crop with great potential for processing into various quality products. Aonla preserve making is an important economic activity in our country. The pricking methods are age old, hence a hand operated aonla pricking machine was introduced in preserve making industries to speed up the pricking task. OWAS and RULA two of the most commonly used ergonomic assessment tools were evaluated for their efficacy in the assessment pricking along with Rating of perceived exertion scale. Analysis of working posture using RULA revealed that the pricking task with existing methods i.e. fork and hand tool requires immediate investigation and changes in working posture while with machine pricking investigations and changes are required soon. The results of OWAS indicated that the posture maintained while pricking with existing methods need to be changed in future planning while with machine was acceptable. The subjective assessment revealed that machine pricking was less exerting activity as compared to the existing methods. The preserve prepared from machine pricked fruit was most acceptable among consumers. Hence, in the form of machine ergonomic intervention was brought about in preservation industries which have proved beneficial for workers in terms of their safety and productivity.     

Moving beyond the employee: The role of the organizational context in leader workplace aggression

Management and psychology scholars are increasingly seeking to examine how organizational characteristics that contextualize leadership shape the occurrence, impact, and prevention of leader workplace aggression. However, a comprehensive review of this literature has not yet been conducted, so a systematic understanding is lacking regarding questions including: (1) when, why and how is such aggression more likely to occur; (2) how do contextual factors enable or constrain effects of these leader behaviors on employees; and (3) how can organizations proactively manage their internal dynamics to prevent or reduce such incidences? Drawing on Porter and McLaughlin's (2006) components of organizational context, I review existing leader aggression research that intersects with seven categories: (1) culture/climate; (2) goals/purposes; (3) people/composition; (4) processes; (5) state/condition; (6) structure; and (7) time. I then offer theoretical propositions for future work, which are grounded in the roles and responsibilities inherent to the nature of leadership and coupled with the changing nature of organizational life. As a result, I set the research agenda for the next decade of organizational context × leader workplace aggression studies.     

On some test statistics for testing homogeneity of variances: a comparative study

In this paper, we have reviewed 25 test procedures that are widely reported in the literature for testing the hypothesis of homogeneity of variances under various experimental conditions. Since a theoretical comparison was not possible, a simulation study has been conducted to compare the performance of the test statistics in terms of robustness and empirical power. Monte Carlo simulation was performed for various symmetric and skewed distributions, number of groups, sample size per group, degree of group size inequalities, and degree of variance heterogeneity. Using simulation results and based on the robustness and power of the tests, some promising test statistics are recommended for practitioners.     

Analysis of Bivariate Survival Data using Shared Inverse Gaussian Frailty Model

In this article, we consider shared frailty model with inverse Gaussian distribution as frailty distribution and log-logistic distribution (LLD) as baseline distribution for bivariate survival times. We fit this model to three real-life bivariate survival data sets. The problem of analyzing and estimating parameters of shared inverse Gaussian frailty is the interest of this article and then compare the results with shared gamma frailty model under the same baseline for considered three data sets. Data are analyzed using Bayesian approach to the analysis of clustered survival data in which there is a dependence of failure time observations within the same group. The variance component estimation provides the estimated dispersion of the random effects. We carried out a test for frailty (or heterogeneity) using Bayes factor. Model comparison is made using information criteria and Bayes factor. We observed that the shared inverse Gaussian frailty model with LLD as baseline is the better fit for all three bivariate data sets.     

A Selection Procedure for Selecting the Least Increasing Failure Rate Average Distribution

For k independent absolutely continuous increasing failure rate average (IFRA) life distributions F_i, i = 1, 2, …, k, Link (1989 Link, W.A. (1989). Testing for exponentiality against monotone failure rate average alternatives. Commun. Statist. Theor. Meth. 18(8): 3009–3017.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) considered a measure of departure of against monotone failure rate average alternatives. In this paper, we use the measure defined by Link for detection of IFRA-ness of life distribution F_i. A two-stage selection procedure to select the least IFRA distribution is proposed. This selection procedure is based on a U-statistic which is an estimator of the measure and can be implemented even when the IFRA life distributions belong to different families. The applications of this procedure are discussed for some well known distributions.     

Some Effective Rotation Patterns in Estimation of Population Mean in Two-Occasion Successive Sampling

This article is an attempt to explore some effective rotation patterns in estimation of current population mean in two occasions successive sampling. Utilizing the readily available information on an auxiliary variable on both occasions and the information on study variable from the previous occasion, some efficient estimation procedures have been suggested. Optimum replacement strategies and the efficiencies of the proposed estimators have been discussed. Empirical studies are carried out and suitable recommendations are made.     

On metric dimension of plane graphs with $$\frac{m}{2}$$ number of 10 sided faces

Journal of Combinatorial Optimization - Let $$\Gamma =\Gamma (V, E)$$ be a simple (multiple edges and loops are not considered), connected (every pair of distinct vertices are joined by a path),...