Bayesian estimation for the Pareto income distribution

The Bayes estimators of the Gini index, the mean income and the proportion of the population living below a prescribed income level are obtained in this paper on the basis of censored income data from a pareto income distribution. The said estimators are obtained under the assumptions of a two-parameter exponential prior distribution and the usual squared error loss function. This work is also extended to the case when the income data are grouped and the exact incomes for the individuals in the population are not available. The method for the assessment of the hyperparameters is also outlined. Finally, the results are generalized for the doubly truncated gamma prior distribution. Now deceased.     

Estimating time to detect time trends in continuous cropping

SUMMARY In long-term field trials comparing different sequences of crops and husbandry practices, the identification and understanding of trends in productivity over time is an important issue of sustainable crop production. This paper presents a statistical technique for the estimation of time trends in yield variables of a seasonal annual crop under continuous cropping. The estimation procedure incorporates the correlation structure, which is assumed to follow first-order autocorrelation in the errors that arise over time on the same plot. Because large differences in annual rainfall have a major effect on crop performance, rainfall has been allowed for in the estimation of the time trends. Expressions for the number of years (time) required to detect statistically significant time trends have been obtained. Illustrations are based on a 7-year data set of grain and straw yields from a trial in northern Syria. Although agronomic interpretation is not intended in this paper, the barley yield data indicated that a significant time trend can apparently be detected even in a suboptimal data set of 7 years' duration.     

An alternative estimator for multiple characteristics in PPS sampling

The problem considered relates to large-scale sample surveys. A new estimator of population total for the characteristics that are poorly correlated with the selection probabilities has been developed for the PPSWR sampling scheme. The relative efficiency of the proposed estimator has been studied under a super-population model. A numerical investigation into the performance of the estimator has also been made.     

Detecting diagnostic accuracy of two biomarkers through a bivariate log-normal ROC curve

In biomedical research, two or more biomarkers may be available for diagnosis of a particular disease. Selecting one single biomarker which ideally discriminate a diseased group from a healthy group is confront in a diagnostic process. Frequently, most of the people use the accuracy measure, area under the receiver operating characteristic (ROC) curve to choose the best diagnostic marker among the available markers for diagnosis. Some authors have tried to combine the multiple markers by an optimal linear combination to increase the discriminatory power. In this paper, we propose an alternative method that combines two continuous biomarkers by direct bivariate modeling of the ROC curve under log-normality assumption. The proposed method is applied to simulated data set and prostate cancer diagnostic biomarker data set.     

Human Capital Attainment and Gender Empowerment: The Kerala Paradox*

Objectives. The State of Kerala in southwestern India shows the highest gender development index in the country. Despite having the highest literacy rate and educational achievements of women, the suicide rate among females is very high, and domestic violence committed against women is increasing every year in Kerala. This article attempts to analyze the demographic, social, and cultural changes that are occurring in order to understand this apparent paradox of high human capital attainment and high violence and suicides experienced by women in Kerala. Methods. The study uses data from the Census of India (1991, 2001) , National Crime Records Bureau (1998–2000), and Reproductive and Child Health ( District Level House Hold Survey—2001 ) to analyze trends in crime, violence, and suicide rates, and demographic profiles of the different districts in Kerala. Results. High educational attainment has fostered new aspirations and attitudes among women in Kerala. Yet, societal and cultural norms still dictate that women should be subservient to men both at home and in the labor market. This imbalance often contributes to family violence and suicides in Kerala. Thus, beneath the veil of development lie some disturbing social, cultural, and economic issues that may be contributing to high rates of suicide and family violence in Kerala. Conclusions. This study demonstrates that high educational attainment alone will not promote gender empowerment unless the social and cultural fabric of a country or state ensures equality of women in all areas of life.     

Workers’ Remittances to India: An Examination of Transfer Cost and Efficiency

Regarding the time efficiency of remittance transfer channels to India, the evidence suggests that traditional banking instruments are relatively inefficient as compared to the new information technology‐enabled products. Transfer arrangement of the Indian banks with overseas exchange houses has reduced the settlement cycle and the cost. Both the banks and money transfer operators (MTOs) are able to keep the transaction cycle low through the use of information technology‐enabled formats. Given that the average cost curve of the banks is located to the right of the average cost curve of the MTOs, greater potential exists for the improvement in overall efficiency of the two entities, particularly through the sharing of messaging and the access and disbursement networks to reduce the overhead cost. The estimates of error correction model reveal that the transaction fee and payment infrastructure are significant determinants of remittance flows, underscoring the scope of policy measures in influencing remittance inflows. The estimates indicate that over the medium to long‐term horizon, transaction cost emerges as the most dominant variable explaining the variation in remittances. The payments infrastructure also explains about 10 per cent variation in remittances over the medium‐term. The impulse response analysis further reveals that the favourable shocks to transaction fees and the payments infrastructure cause steady improvement in remittance inflows over the medium‐term horizon, thus underlining the importance of cost and efficiency in affecting the workers’ remittances.     

On Non-parametric Estimation of the Survival Function with Competing Risks

The non-parametric maximum likelihood estimators (MLEs) are derived for survival functions associated with individual risks or system components in a reliability framework. Lifetimes are observed for systems that contain one or more of those components. Analogous to a competing risks model, the system is assumed to fail upon the first instance of any component failure; i.e. the system is configured in series. For any given risk or component type, the asymptotic distribution is shown to depend explicitly on the unknown survival function of the other risks, as well as the censoring distribution. Survival functions with increasing failure rate are investigated as a special case. The order restricted MLE is shown to be consistent under mild assumptions of the underlying component lifetime distributions.     

Identification of composite (∑+II) arma models by relatively simpler models

In the real world situations, many time series are aggregates of two or more time series. An aggregation may take place due to an addition or the product or both of two or more time series. We are often interested in the study of the properties of aggregates which are, in turn, dependent on the properties of the constituent series. Motivated by this problem, the authors study in this paper the properties of models generated by the operator (Σ+II) on autoregressive-moving-average (ARMA) processes of orders (p_i,q_i), i = l→n . A few practical examples where such models have been used are given in the introduction and an illustrative numerical example is discussed at the end of the paper.     

Robust test for means when population variances are unequal

We consider the problem of testing the equality of two population means when the population variances are not necessarily equal. We propose a Welch-type statistic, say T^* _c, based on Tiku!s ‘1967, 1980’ modified maximum likelihood estimators, and show that this statistic is robust to symmetric and moderately skew distributions. We investigate the power properties of the statistic T^* _c; T^* _c clearly seems to be more powerful than Yuen's ‘1974’ Welch-type robust statistic based on the trimmed sample means and the matching sample variances. We show that the analogous statistics based on the ‘adaptive’ robust estimators give misleading Type I errors. We generalize the results to testing linear contrasts among k population means