Percentage points of LRC for testing equality of covariance matrices under intraclass correlation structure

The exact null distribution of the likelihood ratio test statistic for testing equality of covariance matrices of q compound symmetric Gaussian models (bivariate or trivariate) has been obtained and percentage points for q ? 5 have been computed. The inverse Mellin transform and calculus of residues have been used to derive these results.     

A regression estimator for finite population mean of a sensitive variable using an optional randomized response model

Kalucha et al. (Kalucha G., Gupta S., Dass B. K. (accepted). Ratio estimation of finite population mean using optional randomized response models. Journal of Statistical Theory and Practice) introduced an additive ratio estimator for finite population mean of a sensitive variable in simple random sampling without replacement and showed that this estimator performs better than the ordinary mean estimator based on an optional randomized response technique (RRT). In this paper, we introduce a regression estimator that performs better than the ratio estimator even for the modest correlation between the study and the auxiliary variables. A comparison of the proposed estimator with the corresponding ratio estimator and the ordinary RRT mean estimator is carried out theoretically, and is also illustrated with a simulation study.     

Non-central bivariate beta distribution

Let U, V and W be independent random variables, U and V having a gamma distribution with respective shape parameters a and b, and W having a non-central gamma distribution with shape and non-centrality parameters c and δ, respectively. Define X = U/(U + W) and Y = V/(V + W). Clearly, X and Y are correlated each having a non-central beta type 1 distribution, X ~ NCB1 (a,c;d){X \sim {\rm NCB1} (a,c;\delta)} and Y ~ NCB1 (b,c;d){Y \sim {\rm NCB1} (b,c;\delta)} . In this article we derive the joint probability density function of X and Y and study its properties.     

An extension of the generalized exponential distribution

The two-parameter generalized exponential distribution has been used recently quite extensively to analyze lifetime data. In this paper the two-parameter generalized exponential distribution has been embedded in a larger class of distributions obtained by introducing another shape parameter. Because of the additional shape parameter, more flexibility has been introduced in the family. It is observed that the new family is positively skewed, and has increasing, decreasing, unimodal and bathtub shaped hazard functions. It can be observed as a proportional reversed hazard family of distributions. This new family of distributions is analytically quite tractable and it can be used quite effectively to analyze censored data also. Analyses of two data sets are performed and the results are quite satisfactory.     

The context of decision-making in cases of child neglect

This paper explores professional decision-making in cases of child neglect within the context of child protection practice in Britain. The literature on the nature of neglect is reviewed. Difficulties associated with decision-making are then examined within a framework that addresses the social, political and organizational context of child protection practice. It is argued that the current system, which focuses on incidents of abuse rather than the context of children's lives, provides inadequate protection for many children experiencing chronic neglect. Conclusions are drawn with regard to the development of practice that supports vulnerable parents while still remaining the child's welfare as paramount. © 1998 John Wiley & Sons, Ltd.     

A generalized class of estimators under two-phase stratified sampling for non response

In this paper, we propose a generalized class of estimators for finite population mean using two auxiliary variables in two-phase stratified sampling for non response. We identify 17 estimators as special cases of the proposed class of estimators. Expressions for the bias and mean squared error (MSE) of estimators are obtained up to first order of approximation. A data set is used for efficiency comparisons.     

Solving hybrid flow shop problem using energetic reasoning and global operations

This paper shows that the use of satisfiability tests and time-bound adjustments based on energetic reasoning and global operations can enhance the efficiency of branch and bound procedures for optimally solving the hybrid flow shop scheduling problem. Procedures to use energetic reasoning and extended forms of global adjustment techniques are described and are empirically evaluated. Computational results show that the proposed approaches outperform the best known procedures to optimally solve the hybrid flow shop problem.     

On Kronecker block designs for factorial experiments

In this paper the use of Kronecker designs for factorial experiments is considered. The two-factor Kronecker design is considered in some detail and the efficiency factors of the main effects and interaction in such a design are derived. It is shown that the efficiency factor of the interaction is at least as large as the product of the efficiency factors of the two main effects and when both the component designs are totally balanced then its efficiency factor will be higher than the efficiency factor of either of the two main effects. If the component designs are nearly balanced then its efficiency factor will be approximately at least as large as the efficiency factor of either of the two main effects. It is argued that these designs are particularly useful for factorial experiments.Extensions to the multi-factor design are given and it is proved that the two-factor Kronecker design will be connected if the component designs are connected.     

ON SOME PRODUCT TYPE ESTIMATORS IN VARYING PROBABILITY1

It is shown that varying probability in product method estimation increases the efficiency of estimate under some usual conditions. Further, a necessary condition, for the product estimate from a sample drawn with pps and without replacement to be more efficient than the product estimate from a sample drawn with pps and replacement, has been obtained; incidentally, it is the same as obtained by Narain (1951) for varying probability without replacement to be more efficient than varying probability with replacement. The use of the R.H.C. sampling scheme has also been suggested, and its variance and bias has been shown to be always less than that of pps with replacement.     

On the determination of mixing density in reliability studies

In reliability studies the three quantities (1) the survival function, (2) the failure rate and (3) the mean residual life function are all equivalent in the sense that given one of them, the other two can be determined. In this paper we have considered the class of exponential type distributions and studied its mixture. Given any one of the above mentioned three quantities of the mixture a method is developed for determining the mixing density. Some examples are provided as illustrations. Some well known results follow trivially.