Prevalence and economic well-being of families raising multiple children with disabilities

This study estimates the prevalence of households raising more than one child with disabilities, and examines these families' economic well-being. Using pooled data from the 2004 and 2008 Survey of Income and Program Participation we compare households with multiple children with disabilities (n = 932) to households with one disable child (n = 3457) and to households with at least one child but none with disabilities (n = 21,378) on measures of material hardship. Three percent of U.S. households with children had more than one disabled child. Compared to other households with children, those with multiple children with disabilities were significantly more likely to have income below the federal poverty level and to report material hardships. The number of children with disabilities is an important contextual variable for studying the economic circumstances under which, care is provided to children with disabilities. Its implications for practice and policy are discussed.     

A New Two‐Bin Policy for Inventory Systems with Differentiated Demand Classes

We consider an inventory system under continuous review with two demand classes that are different in terms of service level required (or penalty cost incurred for backordering of demand). Prior literature has proposed the critical level rationing (CLR) policy under which the demand from the lower priority class is backordered once inventory falls below the critical level. While this reduces the penalty cost for the higher demand class, the fill rate achieved for the lower priority demand class gets compromised. In this study, we propose a new class of two‐bin (2B) policy for the problem. The proposed 2B policy assigns separate bins of inventory for the two demand classes. The demand for each class is fulfilled from its assigned bin. However, when the bin intended for the higher demand class is empty, the demand from the higher class can still be fulfilled with the inventory from the other bin. The advantage of the 2B policy is that better fill rates are achieved, especially for the lower demand class. Computational results show that the proposed policy is able to provide a much higher service level for the lower priority class demand without increasing the total cost too much and without affecting the service level for the higher priority class. When a service level constrained optimization problem is considered, the 2B policy dominates the CLR policy when the service level difference for the two classes is not too high or the service levels required for both the classes are relatively lower.     

Root-n-consistent Estimation in Partial Linear Models with Long-memory Errors

We consider estimation of β in the semiparametric regression model y ( i ) - x ^T( i )β + f ( i / n ) + ε( i ) where x ( i ) = g ( i )/ n ) + e ( i , f and g are unknown smooth functions and the processes ε( i ) and e ( i ) are stationary with short- or long-range dependence. For the case of i.i.d. errors, Speckman (1988) proposed a √ n –consistent estimator of β. In this paper it is shown that, under suitable regularity conditions, this estimator is asymptotically unbiased and √ n –consistent even if the errors exhibit long-range dependence. The orders of the finite sample bias and of the required bandwidth depend on the long-memory parameters. Simulations and a data example illustrate the method     

On priors that match posterior and frequentist distribution functions

In the multiparameter case, this paper characterizes priors so as to match, up to o(n^-1/2), the posterior joint cumulative distribution function (c.d.f.) of a posterior standardized version of the parametric vector with the corresponding frequentist c.d.f.     

Determination of optimum experimental conditions using dispersion main effects and interactions of factors in replicated factorial experiments

Dispersion main effects and two-factor interactions are first defined and then estimated in replicated factorial experiments. A method based on Union-Intersection rules, using dispersion main effects and two factor interactions is proposed for finding the level combinations of control factors so that the response variability due to noise is minimum. Illustrative examples are also given.     

Applications of empirical characteristic functions in some multivariate problems

In this note we extend univariate tests for normality and symmetry based on empirical characteristic functions to the multivariate case.     

Commodity market stabilization: A comparison of simple and optimal intervention strategies in the world copper market

With the publication of the Brandt Report, international commodity policy has again become an important issue. Commodity stabilization agreements have been proposed as a means of stabilizing producers' incomes and/or redistributing wealth to less developed economies. This paper examines, in the context of a single market, the extent to which prices can be stabilized, the potential costs of such a scheme, and whether this redistribution would be achieved. By comparing the bandwidth rules that have been proposed with optimal stabilization rules, we find that significant stabilization is possible but expensive and that bandwidth rules are likely to prove inadequate because they cannot anticipate.     

Two normal approximations to the binomial distribution

Two new normal approximations are proposed for the cumulative binomial distribution when the mean-is reasonably large. Their adequacy is compared with that of certain well-known approximations- The first is recommended for its simplicity and accuracy relative to the standard and Gram-Charlier approximations. The second Is shown to be more accurate than all known approximations for a certain range of the probability of success.     

Influential observations in view of design and inference

In this paper we consider the measures for detecting the influential observations w.r.t. one or several parameters of interest at the design stage. We also consider the Cook's measure for detecting the influential observations at the inference stage. We study the interrelationship between two kinds of measures.