La médiane simpliciale d'Oja: Existence,unicité et stabilité

Oja (1983) examined various ways of measuring location, scatter, skewness, and kurtosis for multivariate distributions. Among other measures of location, he introduced a generalised median known in this paper under the name of the Oja median. In our study of the existence of that median, we show that Oja's definition can only be applied to distributions having a mean. In dimension d θ 2, we establish that the usual method of extension breaks down, which raises the question of the validity of the concept as a notion of median. Two fundamental theoretical properties of that median are also considered: uniqueness and consistency.     

Maternal employment in Scandinavia: a comparison of the after-birth employment activity of Norwegian and Swedish women

A striking characteristic of recent Western labour market trends is the rise in employment among mothers of very young children. So far, few studies have analysed the impact of public policies on employment rates of young mothers. In this study we address this issue by comparing two similar countries, Norway and Sweden, which have the same set of policies with slight variations, using data sets with similar designs. We analyse rates of re-entry into paid work after first birth for mothers in 1968–88 by means of hazard regression. One important finding is that the right to paid maternity leave with jobsecurity greatly speeds up the return to work.We want to thank Jan Kowalski for programming assistence and the Swedish Research Council for the Social Sciences and the Swedish Council for Research in the Humanities and Social Sciences for financial support for the Swedish study. We are grateful to John F. Ermisch, Siv Gustafsson, to two anonymous referees and to colleagues at the Demography Unit for valuable comments. Responsible editors. Siv S. Gustafsson, John F. Ermisch.     

Bequests as a heir "disciple device."

This paper develops a model ofinter vivos gifts and bequests in a setting of moral hazard and adverse selection. Altruistic parents do not perfectly know how much effort their children make to earn their living, nor do they know their true level of ability.Inter vivos gifts take place prior to the realization of the children's earnings whereas at the moment of bequests, parents do observe them. We show that an optimal transfer policy generally uses a mix ofinter vivos gifts — deemed as more efficient — and bequests — deemed as more redistributive.We are thankful to Allessandro Cigno, Jacques Cremer, Claude d Aspremont and anonymous referees for their comments.Responsible editor: Alessandro Cigno     

Modeling household fertility decisions with generalized Poisson regression

This paper models household fertility decisions by using a generalized Poisson regression model. Since the fertility data used in the paper exhibit under-dispersion, the generalized Poisson regression model has statistical advantages over both standard Poisson and negative binomial regression models, and is suitable for analysis of count data that exhibit either over-dispersion or under-dispersion. The model is estimated by the method of maximum likelihood. Approximate tests for the dispersion and goodness-of-fit measures for comparing alternative models are discussed. Based on observations from the Panel Study of Income Dynamics of 1989 interviewing year, the empirical results support the fertility hypothesis of Becker and Lewis (1973). Received January 7, 1997 /Accepted April 3, 1997     

Network analysis in evaluation: some words of caution

Network analysis, a methodology derived from general systems' theory, can be utilized as a community mental health administrative-evaluation procedure. Evaluation parameters derived from analysis of patient data as they “flow” through a network of agency services, provide measures of systemic functioning. These parameters include “longest paths” and various ratio relationships as evaluation measures of service delivery. The limitations of network analysis are examined by means of conceptual analyses, and phenomena that emerged from research experience. The necessity for both quantitative and qualitative data to ensure a meaningful evaluation of mental health services is explained. Conclusions about the value of the network analysis approach are considered.     

Involving constituents in agency priority setting: a case study

Many government agencies have "constituents" who believe the agencies should hear and consider their needs and desires in establishing program priorities. This article describes how one involves interested constituents (consumers, industry, medical professionals, and state organizations) in the agency's annual priority-setting process. This participation has produced a number of beneficial results-some expected and some unexpected.     

The utilization of prevailing evaluation policy in the selection of performance measures

This study considers the problem of inferring a functional evaluation criterion from existing performance measure policies. The objective is to develop a rational basis by which to adaptively evaluate a current best set of performance measures from alternative sets. The analysis is based on a matrix approach for relating system characteristics to performance measures across a set of activities. A procedure for ranking measure combinations which are candidate implementation alternatives is devised using this matrix representation and cost information. An example illustrating the procedure is presented.     

A two phases queueing system with Bernoulli vacation schedule under multiple vacation policy

This paper deals with a single server Poisson arrival queue with two phases of heterogeneous service along with a Bernoulli schedule vacation model, where after two successive phases service the server either goes for a vacation with probability p (0≤p≤1) or may continue to serve the next unit, if any, with probability q(=1−p). Further the concept of multiple vacation policy is also introduced here. We obtained the queue size distributions at a departure epoch and at a random epoch, Laplace Stieltjes Transform of the waiting time distribution and busy period distribution along with some mean performance measures. Finally we discuss some statistical inference related issues.     

The cost of children: May the collective approach to household behavior help?

The collective approach to household consumption behavior tries to infer from variables supposed to affect the general bargaining position of household members information on the allocation of consumptions goods and tasks among them. This paper investigates the extension of previous work to the case where children may be considered as a public consumption good by the two adult members of a household. The main question being asked is whether it is possible to retrieve from the aggregate consumption behaviour of the household and the relative earnings of the parents information on the allocation of goods between them and children. This alternative approach to the estimation of the ‘cost of children’ is contrasted with the conventional approach based on a ‘unitary’ representation of and demographic separability assumptions on household consumption behaviour. Received: 29 August 1997/Accepted: 26 November 1998