《中国统计年鉴》：政府统计窗口建设的回顾与展望

《中国统计年鉴》是显示中国发展状况的窗口,也是显示中国政府统计能力的窗口。本文以纵向历史变化为主线,首先回顾了《年鉴》从无到有和后续演变的全过程,着力发掘变化背后的原因和力量;然后着眼未来建设,对《年鉴》的内容架构和基本定位做了比较深入的讨论。     

Lorenz ordering of order statistics from log-logistic and related distributions

This paper obtains Lorenz ordering relationships among order statistics from log-logistic samples of possibly different sizes. Some results extend other families including the Lomax, Burr III and Burr XII distributions.     

Measuring diversity in biological populations with logarithmic abundance distributions

Fisher's logarithmic distribution for species abundance is derived under a suitable set of conditions. The derivation explains the explicit meaning of the two parameters of the distribution.     

On partial sufficiency: A review

The notion of a sufficient statistic—a statistic that summarizes in itself all the relevant information in the sample x about the universal parameter ω—is acclaimed as one of the most significant discoveries of Sir Ronald A. Fisher. It is however not well-recognized that the related notion of a partially sufficient statistic—a statistic that isolates and exhausts all the relevant and usable information in the sample about a sub-parameter θ=θ(ω)—can be very elusive if the question is posed in sample space terms. In this review article, the author tries to unravel the mystery that surrounds the notion of partial sufficiency. For mathematical details on some of the issues raised here one may refer to Basu (1977).     

A COMPARISON OF TESTS OF UNIFORMITY FOR SPHERICAL DATA

A comparison is made af three tests of uniformity for spherical vector data, and of the corresponding tests of uniformity for spherical axial data.     

Pitfalls in linear models for style analysis

We discuss the statistical properties of return-based OLS style analysis introduced by Sharpe (1992). The aim of style analysis is to infer a fund managers investment decisions using only publicly available data on the fund performance and on the time evolution of market indexes. We show that the model proposed by Sharpe suffers of relevant drawbacks, most notably that it fails to yield correct results even in the simple case of a buy-and-hold strategy that only invests in the market indexes. Under this hypothesis we show that a model linear in index levels, as opposed to index returns, estimated via a Kalman filter avoids Sharpes model drawbacks. We further extend our analysis to strategies where the fund manager policy changes with time and the asset classes in which the fund manager invests are not known exactly. In this last case we show that a style analysis is possible only conditional to either an orthogonality hypothesis on the active investment strategy, or by the introduction of suitable instrumental variables.The authors are grateful to the editor and an anonymous referee for many comments which greatly helped in improving the paper. The authors are, obviously, fully responsible for any remaining error.     

Approximate maximum likelihood predictors of future failure times of shifted exponential distributions under multiple type II censoring

Suppose we consider a general multiple type II censored sample (some middle observations being censored) from a shifted exponential distribution. The maximum likelihood prediction method does not admit explicit solutions. We introduce a simple approximation to one of prediction likelihood equations and derive approximate predictors of missing failure times. We compute their mean square prediction errors by simulation and compare them with the best linear predictors. Further, we present two real examples to illustrate this method of prediction.AMS Subject Classification (2000): 62G30, 62M20, 62F99