Pooling states in the multinomial logit model: degrees of freedom. A correction

Received: October 4, 2000     

Restricted optimal progressive censoring

Unlike traditional Type I and II censoring, progressive censoring allows for removal of surviving units throughout the life test. This feature has several benefits and in the literature, much work has been done on inference based on progressively censored samples and identifying optimal progressive censoring schemes. In this paper, we introduce restricted progressive censoring and within this class, the problem of identifying optimal schemes under different minimum variance criteria. We explore these plans geometrically as well as provide some useful properties. In particular, we look at the vertices of the set of admissible plans and their role in approximating optimal plans. We also provide computational results for illustrative purposes.     

Association of progressively Type-II censored order statistics

The association of progressively Type-II censored order statistics from a sample of associated random variables _X1,…,_Xn$X_1,\dots ,X_n$ is established. Moreover, some bivariate dependence properties are discussed for independent but not necessarily identically distributed _X1,…,_Xn$X_1,\dots ,X_n$.     

Fisher information in generalized order statistics

A representation of the Fisher information in generalized order statistics in terms of the hazard rate of the underlying distribution function is derived under mild regularity conditions. This expression supplements results for complete, Type-II censored, and progressively Type-II censored data. As a byproduct, we find a hazard rate based representation for samples of k-records which apparently has not been known so far. Moreover, sufficient conditions for the validity of this representation in location and scale family settings are given. The result is illustrated by considering generalized order statistics based on logistic, Laplace, and extreme value distributions.     

Laplace record data

Basic properties of upper record values _XT(1),_XT(2),…,_XT(n)$X_{T(1)},X_{T(2)},\dots ,X_{T(n)}$ from a symmetric two-parameter Laplace distribution are established. In particular, unimodality of the density function and the exact expression of the mode are derived. Moreover, we obtain approximations of the first and second moment and the variance of _XT(k)$X_{T(k)}$ which provide close approximations even for moderate k. Additionally, limit laws and simulation of Laplace records are considered. Finally, we discuss maximum likelihood estimation in a location-scale family of Laplace distributions. We obtain nice representations of the estimators provided that the location parameter is unknown and present interesting properties of the established estimators. Some illustrative examples complete the presentation.     

Modification of autoregressive fractionally integrated moving average models for the estimation of persistence

In this paper, it is proposed to modify autoregressive fractionally integrated moving average (ARFIMA) processes by introducing an additional parameter to comply with the criticism of Hauser et al . (1999) that ARFIMA processes are not appropriate for the estimation of persistence, because of the degenerate behavior of their spectral densities at frequency zero. When fitting these modified ARFIMA processes to the US GNP, it turns out that the estimated spectra are very similar to those obtained with conventional ARFIMA models, indicating that, in this special case, the disadvantage of ARFIMA models cited by Hauser et al. (1999) does not seriously aff ect the estimation of persistence. However, according to the results of a goodness-of-fit test applied to the estimated spectra, both the ARFIMA models and the modified ARFIMA models seem to overfit the data in the neighborhood of frequency zero.     

Arbeitskampf mit Nadel und Faden

The film “Made in Dagenham”, produced by the British director Nigel Cole, focuses on the turbulent times of the first labor dispute led by women in British history. The sewing machinists strike at the Ford Dagenham plant in 1969 was a major step towards gender equality in the workplace and initiated the “Equal Pay Law” which was passed in 1970 in England. The film is a cinematic monument to women and at the same time an adorable comedy characterized by a typical British sense of humor. This contribution addresses the continuing discrimination of women in employment as well as the male chauvinist culture of trade unions.     

Relation for joint densities of progressively censored order statistics

A relation between four joint densities of progressively type-II censored order statistics is shown, which is well known in the particular case of ordinary order statistics. The result leads to identities for product moments and for moments of contrasts.     

Dependence structure of generalized order statistics

In this article, simple expressions for marginal density functions of multiply censored generalized order statistics based on continuous distribution functions are obtained. Moreover, it is shown that generalized order statistics are multivariate totally positive and, thus, associated. This property is applied to show that regressions of generalized order statistics are nondecreasing under weak conditions.