Estimation of Mode Using Two-phase Sampling

In this article, we consider the problem of estimation of mode using two-phase sampling. Ratio- and difference-type estimators in two-phase sampling are proposed. The asymptotic properties of the proposed estimators are studied analytically as well as empirically for different situations for the given cost of surveys. The use of two-phase sampling has been found to be cost saving design while estimating mode by making a proper use of auxiliary information.     

Edge Estimation in the Population of a Binary Tree Using Node-Sampling

Suppose a finite population of several vertices, each connected to single or multiple edges. This constitutes a structure of graphical population of vertices and edges. As a special case, the graphical population like a binary tree having only two child vertices associated to parent vertex is taken into consideration. The entire binary tree is divided into two sub-graphs such as a group of left-nodes and a group of right-nodes. This paper takes into account a mixture of graph structured and population sampling theory together and presents a methodology for mean-edge-length estimation of left sub-graph using right edge sub-graph as an auxiliary source of information. A node-sampling procedure is developed for this purpose and a class of estimators is proposed containing several good estimators. Mathematical conditions for minimum bias and optimum mean squared error of the class are derived and theoretical results are numerically supported with a test of 99% confidence intervals. It is shown that suggested class has a sub-class of optimum estimators, and sample-based estimates are closer to the true value of the population parameter.     

Inequality of Opportunity in Indian Women

Social Indicators Research - Inequality of opportunity (IOp) in any society is defined as that part of overall inequality which arises from factors beyond the control of an individual...     

Robust Spatial Analysis of Rare Crimes: An Information‐Theoretic Approach

In this paper we describe a semiparametric information‐theoretic framework for modeling the determinants of rare events aggregated at intracity areal units while allowing for various forms of error correlation structures. The approach is applied to an examination of the effects of socioeconomic and demographic macrocharacteristics of communities on the amount of violence they experience. We investigate and find evidence of some instability in these processes across types of violence and level of areal aggregation. However, we also find evidence of a stable predictor—resource deprivation—for all the types of violence analyzed and at both levels of areal aggregation considered. In addition, we find evidence of a spillover effect of a community's resource deprivation on the level of violence its neighboring areas can expect. We discuss our findings in light of their substantive, methodological, and practical implications.     

In-migration and Living Conditions of Young Adolescents in Greater Johannesburg, South Africa

While migration in South Africa has been studied on a broad canvas, there have been few accounts of children's migration and the effects on living conditions and wellbeing. This article compares the access to services, housing and household amenities, and family characteristics of children born in the Greater Johannesburg metropolis with those of in-migrant children. The article also examines other indicators of child wellbeing related to parental care and schooling. In-migrant children, particularly children who have lived previously in rural areas and/or have recently migrated into the city, are significantly disadvantaged in comparison to long-term resident children in terms of parental education and occupation, housing type and ownership, access to electricity, refuse removal, water and sanitation. In-migrant children also live in households that are less likely to have amenities such as a refrigerator, television, washing machine, telephone and motor vehicle. In terms of child indicators, in-migrant children enjoy less frequent parental contact and are twice as likely to start school later than resident children. Whilst urbanisation to South Africa's metropolitan centres is generally associated with several widely recognised benefits, for children, these benefits may be tempered by the disadvantages of in-migrant families known to be associated with child wellbeing.     

A class of partially linear single‐index survival models

The authors define a class of “partially linear single‐index” survival models that are more flexible than the classical proportional hazards regression models in their treatment of covariates. The latter enter the proposed model either via a parametric linear form or a nonparametric single‐index form. It is then possible to model both linear and functional effects of covariates on the logarithm of the hazard function and if necessary, to reduce the dimensionality of multiple covariates via the single‐index component. The partially linear hazards model and the single‐index hazards model are special cases of the proposed model. The authors develop a likelihood‐based inference to estimate the model components via an iterative algorithm. They establish an asymptotic distribution theory for the proposed estimators, examine their finite‐sample behaviour through simulation, and use a set of real data to illustrate their approach.     

Non-parametric recursive estimates of a probability density function and its derivatives

Recursive estimates of a probability density function (pdf) are known. This paper presents recursive estimates of a derivative of any desired order of a pdf. Let f be a pdf on the real line and p?0 be any desired integer. Based on a random sample of size n from f, estimators f^(p)_n of f^(p), the pth order derivatives of f, are exhibited. These estimators are of the form $\text{n}{}^{\mathrm{?1}}\text{∑n}\text{j=1}\text{δ}{}_{\mathrm{jp}}$, where δ_jp depends only on p and the jth observation in the sample, and hence can be computed recursively as the sample size increases. These estimators are shown to be asymptotically unbiased, mean square consistent and strongly consistent, both at a point and uniformly on the real line. For pointwise properties, the conditions on f^(p) have been weakened with a little stronger assumption on the kernel function.     

IMPACT OF SEAT BELT USE ON DRIVING BEHAVIOR

Previous research has indicated that individual compensating behavior, specifically, more risky driving may reduce the effectiveness of seat belt laws. We test the compensating-behavior hypothesis using individual-specific survey data. The analysis also incorporates individual risk tastes. Our results indicate that the compensating-behavior hypothesis applies only to those that are not strongly risk averse. Other risk-differentiated groups do not exhibit compensating behavior. Finally, it seems that individuals learn to reduce compensating behavior over time.     

Successful strategies—The story of Singapore Airlines (SIA)

This case study describes the growth and development of Singapore Airlines from a small national carrier serving the Malayan States to an international airline with a network extending to 27 countries. Its strategy is simple: quality service at a competitive price, made possible by high investment in equipment and in staff training.     

A NOTE ON OPTIMUM STRATIFICATION FOR EQUAL ALLOCATION WITH RATIO AND REGRESSION METHODS OF ESTIMATION

When the information on a highly positively correlated auxiliary variable x is used to construct stratified regression (or ratio) estimates of the population mean of the study variable y, the paper considers the problem of determining approximately optimum strata boundaries (AOSB) on x when the sample size in each stratum is equal. The form of the conditional variance function V(y/x) is assumed to be known. A numerical investigation into the relative efficiency of equal allocation with respect to the Neyman and proportional allocations has also been made. The relative efficiency of equal allocation with respect to Neyman allocation is found to be nearly equal to one.