On the construction of m-associate pbib designs II

Some series of m-associate triangular PBIB designs have been constructed. A table of now three associate designs in the range b, v ≦ 100; r, k ≦ 10 with their average efficiencies has been given. These designs with (v, b, r, k) are new in the sense that the existence of two associate PBIB designs (e.f. Clatworthy (1973), John & Turner (1977), Dey (1978)) with these parameters are not known. The constructions presented herein also yield partially balanced weighing designs, nested PBIB designs and PBIB designs for m11111 response exoeriments.     

On a Comparison of Several Competing Estimates of a Univariate Normal Mean by the Multiple Criteria Decision-Making Method

In this article we consider the problem of estimation of the mean of a univariate normal population with an unknown variance when uncertain nonsample prior information about the mean is available. We compare four estimators of the mean, including pretest and shrinkage estimators. The performances of the estimators are compared based on the multiple criteria decision making (MCDM) procedure in order to find the best estimator.     

Admissible linear estimation in singular linear models

The admissibility results of Rao (1976), proved in the context of a nonsingular covariance matrix, are exteneded to the situation where the covariance matrix is singular. Admi.s s Lb Le linear estimators in the Gauss-Markoff model are characterized and admis-sibility of the best linear unbiased estimator is investigated.     

Differential fertility and family limitation in an urban community of Uttar Pradesh

The study relates to an investigation of the fertility pattern of a sample of 1018 wives drawn from Lucknow and Kanpur, the two biggest cities of Uttar Pradesh. The sample is stratified with respect to religion and caste, and income. It reveals significant inter-community differences, Muslims and low-caste Hindus showing nearly equal fertility, and high-caste Hindus and Christians showing comparatively lower levels. The proportion of small families (three children or less) is obviously higher in groups with lower fertility, but there is a wide measure of dispersion in each group. Fertility is seen to decline with a rise in income, but not until we cross the income level of Rs 300 per month. Consistent with the differential trends in fertility, striking variations are also observed in the extent of contraceptive practice in different groups. Groups with lower fertility also show a higher frequency of birth control. Birth controllers have lower fertility than the non-controllers, and birth control appears to play a not inconsequential rôle in causing differential trends in fertility.     

Bayesian analysis of multivariate mortality data with large families

This paper presents a Bayesian method for the analysis of toxicological multivariate mortality data when the discrete mortality rate for each family of subjects at a given time depends on familial random effects and the toxicity level experienced by the family. Our aim is to model and analyse one set of such multivariate mortality data with large family sizes: the potassium thiocyanate (KSCN) tainted fish tank data of O'Hara Hines. The model used is based on a discretized hazard with additional time-varying familial random effects. A similar previous study (using sodium thiocyanate (NaSCN)) is used to construct a prior for the parameters in the current study. A simulation-based approach is used to compute posterior estimates of the model parameters and mortality rates and several other quantities of interest. Recent tools in Bayesian model diagnostics and variable subset selection have been incorporated to verify important modelling assumptions regarding the effects of time and heterogeneity among the families on the mortality rate. Further, Bayesian methods using predictive distributions are used for comparing several plausible models.     

Sensitivity of Bayesian sampling inspection schemes to a non-normal prior distribution

summary In this paper we derive the predictive density function of a future observation under the assumption of Edgeworth-type non-normal prior distribution for the unknown mean of a normal population. Fixed size single sample and sequential sampling inspection plans, in a decisive prediction framework, are examined for their sensitivity to departures from normality of the prior distribution. Numerical illustrations indicate that the decision to market the remaining items of a given lot for a fixed size plan may be sensitive to the presence of skewness or kurtosis in the prior distribution. However, Bayes'decision based on the sequential plan may not change though expected gains may change with variation in the non-normality of the prior distribution.     

Balanced arrays and main-effect plans from regular group-divisible designs

A method of constructing balanced arrays of strength two and corresponding main-effect fractional factorial plans from some regular group-divisible designs is presented. Main-effect fractional factorial plans for three-level factorial experiments are constructed. The plans have reasonably high efficiencies for different single degree of freedom effects.     

On resolvable PBIB designs

Resolvable solutions for some two associate PBIB designs obtained by duplicating some non-resolvable designs are given. For the same designs 2-, 3- and 5-resolvable solutions are reported by Clatworthy (1973). A method of construction and some new resolvable PBIB designs obtained through this are given.     

Control in craft work: The case of production potters

This paper examines the social organization of a craft profession (as opposed to an art world), namely production pottery. The analysis focuses on control as the important dependent variable and examines features of the social organization that may influence the amount of control that a production potter has over matters such as work schedule, product and choice of marketing outlets. One conclusion is that stratification along a time dimension (i.e. the length of time that one has been in the profession) is an important independent variable influencing amount of control. The paper concludes with a brief analysis of the controversy surrounding the concepts of “art” and “craft” as members of the study perceive this distinction. I would like to express my gratitude to Robert R. Faulkner who was a constant source of encouragement and inspiration. Special thanks to him for having carefully read and commented upon the various drafts of this paper.     

An estimated‐score approach for dealing with missing covariate data in matched case–control studies

Matched case–control designs are commonly used in epidemiological studies for estimating the effect of exposure variables on the risk of a disease by controlling the effect of confounding variables. Due to retrospective nature of the study, information on a covariate could be missing for some subjects. A straightforward application of the conditional logistic likelihood for analyzing matched case–control data with the partially missing covariate may yield inefficient estimators of the parameters. A robust method has been proposed to handle this problem using an estimated conditional score approach when the missingness mechanism does not depend on the disease status. Within the conditional logistic likelihood framework, an empirical procedure is used to estimate the odds of the disease for the subjects with missing covariate values. The asymptotic distribution and the asymptotic variance of the estimator when the matching variables and the completely observed covariates are categorical. The finite sample performance of the proposed estimator is assessed through a simulation study. Finally, the proposed method has been applied to analyze two matched case–control studies. The Canadian Journal of Statistics 38: 680–697; 2010 © 2010 Statistical Society of Canada