On arcs with weighted points

In the present paper we start the study of arcs with weighted points in a finite projective plane, and we get some particular results about the existence or non-existence of these arcs.     

Families of Hadamard group divisible designs

By a family of designs we mean a set of designs whose parameters can be represented as functions of an auxiliary variable t where the design will exist for infinitely many values of t. The best known family is probably the family of finite projective planes with υ = b = t² + t + 1, r = k = t + 1, and λ = 1. In some instances, notably coding theory, the existence of families is essential to provide the degree of precision required which can well vary from one coding problem to another. A natural vehicle for developing binary codes is the class of Hadamard matrices. Bush (1977) introduced the idea of constructing semi-regular designs using Hadamard matrices whereas the present study is concerned mostly with construction of regular designs using Hadamard matrices. While codes constructed from these designs are not optimal in the usual sense, it is possible that they may still have substantial value since, with different values of λ₁ and λ₂, there are different error correcting capabilities.     

Construction of Youden hyperrectangles

Youden hyperrectangles are higher-dimensional generalizations of balanced block designs and generalized Youden designs. This kind of design has been shown to be optimal for the elimination of multi-way heterogeneity. In this paper, patchwork and geometric methods are combined to construct Youden hyperrectangles for many parameter values.     

A quest for certain linear spaces on thirty points

We investigate the structure of linear spaces on 30 points which have no lines of sizes 2, 3, 6, 30.     

Response from a policymakers' perspective

The case in point (Tellado, 1984) needs to be defined in terms of a client for the research. The research may also have implications for early intervention to mitigate the problems uncovered in the case study. An important element in the development of problem-solving skills may be linguistic skills. Further research about this variable seems warranted.     

Inference about permutation parameter in large samples

The estimation problem of a permutation parameter on the basis of a random sample of increasing size is considered. A necessary and sufficient condition for the existence of an estimator, asymptotically fully efficient for two different distributions families, is derived. We also study the application of this result to cyclic groups of order two and three.     

Complete designs with blocks of maximal multiplicity

The set of distinct blocks of a block design is known as its support. We construct complete designs with parameters v(?7), k=3, λ=v ? 2 which contain a block of maximal multiplicity and with support size $\text{b}{}^1\text{= (}{}^{\mathrm{v}}{}_3\text{) ? 4(v ? 2)}$. Any complete design which contains such a block, and has parameters v, k, λ as above, must be supported on at most (^v₃) ? 4(v ? 2) blocks. Attention is given to complete designs because of their direct relationship to simple random sampling.     

Meta-analysis of the impact of age structure on fertility

The paper uses a meta-analysis to comparatively evaluate the literature addressing the aggregate relationship between a populations age structure and fertility, as hypothesized by Richard Easterlin. The analysis is based on 334 estimated effects retrieved from 19 studies. The results suggest that several factors undermine the empirical support of the Easterlinian age structure/fertility link. These include the neglect of income, the use of relative cohort size to characterize the age structure, mis-specifications of the relevant age-cohorts, as well as the functional form and estimation technique. The results also suggest that the sample of published estimates possibly suffers from two types of publication bias, an under-representation of insignificant effects for small samples, and bias towards supportive effects in the earlier years followed by a bias towards negative effects as the literature matured.All correspondence to: Brigitte Waldorf. The authors appreciate the insightful comments and suggestions from two anonymous reviewers. The research also benefited from discussions with participants of the International Colloquium on Meta-analysis in Economics, Free University, Amsterdam, The Netherlands, December 2002. Finally, we would like to thank David Brown, Meagan Cahill, Angela Donelson, Calvin Farris, and Melaney Seacat from the University of Arizona for their research assistance. Responsible editor: Junsen Zhang.     

Information in experiments and sufficiency

We define measures of information contained in an experiment which are by-products of the parametric measures of Fisher, Vajda, Mathai and Boekee and the non-parametric measures of Bhattacharyya, Rényi, Matusita, Kagan and Csiszár. We use these measures to compare sufficient experiments according to Blackwell's definition. In particular, we prove that if δ_X and δ_Y are two experiments and δ_X≥δ_Y then l_X≥l_y for all of the above measures.