A new approach to use multivariate auxiliary information in sample surveys

A new approach to form multivariate difference estimator is suggested which does not require the knowledge of unknown population parameters as such. It gives minimum variance among the class of multivariate difference estimators. The performance of this estimator with respect to Des Raj's (J. Amer. Statist. Assoc. 60 (1965), 270–277) multivariate difference estimator is illustrated. Using the information on two auxiliary variates, the robustness of Des Raj's estimator y_d is studied empirically. Two new estimators to estimate population mean/total are developed on the same lines as that of y_d. The performance of these estimators is studied for a wide variety of populations.     

Competitive Priorities in Operations Management

Identifying manufacturers' competitive priorities has long been considered a key element in manufacturing strategy research. However, relatively little effort has been devoted to measurement of these constructs in published research. In this study we develop scales for commonly accepted competitive priorities, cost importance, quality importance, delivery-time importance, and flexibility importance. We assess how well the scales capture the constructs that they represent using data collected from 114 manufacturing plants in the United States. The findings suggest that the instrument developed can provide reliable data and that the constructs measured are valid. In addition, comparisons between pairs of informants representing the same business indicate that the perceptual measures of competitive priorities are as reliable as point estimates of routine, seemingly objective information.     

Socio-Environmental and Behavioral Correlates of Having Ever Had Sexual Intercourse Among Adolescents in Peru: A School-Based Cross-Sectional Study

Objective: We assessed the socio-environmental and behavioral correlates of having ever had sexual intercourse among Peruvian adolescents aged 12–18 years in Lima. Methods: A cross-sectional study was conducted in 2014. Result: Of 950 participants, 26.5% of males and 13.0% of females had ever had sexual intercourse. Early adolescents who ever had sexual intercourse had higher odds of being insulted, being involved in a fight, and smoking; whereas late adolescents having sexual experiences were more likely to be male and to report smoking, alcohol consumption, involvment in a fight, and having no/low parental understanding. Conclusion: An integrated approach is useful in addressing risk behaviors in adolescents.     

Capacity-building needs of minority health nonprofits

This article reports on the results of a statewide assessment of the capacity-building needs of organizations that provide health services to ethnic minority groups in Ohio. The research addressed gaps in knowledge about the specific needs of these organizations for improved effectiveness and long-term sustainability. A telephone survey of 659 organizations, supplemented by focus groups with 37 participants in the state's largest cities, indicated substantial need and interest in capacity-building technical assistance in areas such as revenue-generating activities, marketing and public relations, information technology training, program evaluation, and board leadership development. The limited ability of these organizations to pay for the needed assistance creates challenges for planning approaches to meet these vital needs.     

Sufficient admissibility conditions for scale parameter estimator

Although there are a number of results available for the admissibility of the best translation equivariant estimator of the parameter, there is hardly any stated explicitly for the best scale equivariant estimator of the scale parameter. In this paper, we derive sufficient conditions for the admissibility of the scale parameter estimators and compara them. The derivations use the well known results due to Brown [1], Farrell [2], and Portnoy [3]. The loss function has been taken to be quadratic.     

A new jackknife test for homogeneity of variances

A new jackknife test is proposed to test the equality of variances in several populations. The new test is based on jackknifing one group of observations at a time, instead of one observation in each group as recommended by Miller for a two sample case, and by Layard for several samples. The proposed test is examined, and compared with other tests, in terms of power and robustness with respect to a wide variety of non-normal distributions. It is found that the new test is robust and has reasonably high power for normal as well as for non-normal observations, irrespective of the sample size. Furthermore, the proposed test is certainly superior to all other tests considered here in small to moderate size samples, and is as good as or better than the other tests in large samples, irrespective of the distribution of sampling observations.     

Bayesian Inference in Marshall–Olkin Bivariate Exponential Shared Gamma Frailty Regression Model under Random Censoring

Many analyses in the epidemiological and the prognostic studies and in the studies of event history data require methods that allow for unobserved covariates or “frailties”. We consider the shared frailty model in the framework of parametric proportional hazard model. There are certain assumptions about the distribution of frailty and baseline distribution. The exponential distribution is the commonly used distribution for analyzing lifetime data. In this paper, we consider shared gamma frailty model with bivariate exponential of Marshall and Olkin (1967 Marshall, A.W., Olkin, I. (1967). A multivariate exponential distribution. J. Am. Stat. Assoc. 62:30–44.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) distribution as baseline hazard for bivariate survival times. We solve the inferential problem in a Bayesian framework with the help of a comprehensive simulation study and real data example. We fit the model to the real-life bivariate survival data set of diabetic retinopathy data. We introduce Bayesian estimation procedure using Markov Chain Monte Carlo (MCMC) technique to estimate the parameters involved in the proposed model and then compare the true values of the parameters with the estimated values for different sample sizes.     

Comparison of Frailty Models for Acute Leukemia Data under Gompertz Baseline Distribution

In this article, we consider two different shared frailty regression models under the assumption of Gompertz as baseline distribution. Mostly assumption of gamma distribution is considered for frailty distribution. To compare the results with gamma frailty model, we consider the inverse Gaussian shared frailty model also. We compare these two models to a real life bivariate survival data set of acute leukemia remission times (Freireich et al., 1963 Freireich, E.J., Gehan, E., Frei, E., Schroeder, L.R., Wolman, I.J., Anbari, R., Burgert, E.O., Mills, S.D., Pinkel, D., Selawry, O.S., Moon, J.H., Gendel, B.R., Spurr, C.L., Storrs, R., Haurani, F., Hoogstraten, B., Lee, S. (1963). The effect of 6-mercaptopurine on the duration of steroid-induced remissions in acute leukemia: a model for evaluation of other potentially useful therapy. Blood 21:699–716.[Web of Science ®] , [Google Scholar]). Analysis is performed using Markov Chain Monte Carlo methods. Model comparison is made using Bayesian model selection criterion and a well-fitted model is suggested for the acute leukemia data.