Confidence Intervals for the Scale Parameter of the Power-Law Process

The power-law process (PLP) is a two-parameter model widely used for modeling repairable system reliability. Results on exact point estimation for both parameters as well as exact interval estimation for the shape parameter are well known. In this paper, we investigate the interval estimation for the scale parameter. Asymptotic confidence intervals are derived using Fisher information matrix and theoretical results by Cocozza-Thivent (1997 Cocozza-Thivent , C. ( 1997 ). Processus Stochastiques et Fiabilité des Systèmes . Berlin : Springer-Verlag . [Google Scholar]). The accuracy of the interval estimation for finite samples is studied by simulation methods.     

Generalized Random Sign and Alert Delay models for imperfect maintenance

This paper considers the modelling of the process of Corrective and condition-based Preventive Maintenance, for complex repairable systems. In order to take into account the dependency between both types of maintenance and the possibility of imperfect maintenance, Generalized Competing Risks models have been introduced in “Doyen and Gaudoin (J Appl Probab 43:825–839, 2006)”. In this paper, we study two classes of these models, the Generalized Random Sign and Generalized Alert Delay models. A Generalized Competing Risks model can be built as a generalization of a particular Usual Competing Risks model, either by using a virtual age framework or not. The models properties are studied and their parameterizations are discussed. Finally, simulation results and an application to real data are presented.     

Spurious Rejections with Endogenous Break Unit Root Tests in the Presence of Outliers and Breaks

Unit root tests with structural break developed by Zivot and Andrews (1992 Zivot , E. , Andrews , D. W. K. ( 1992 ). Further evidence on the great crash, the oil price shock and the unit root hypothesis . Journal of Business and Economic Statistics 10 : 251 – 270 .[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) and Perron and Rodriguez (2003 Perron , P. , Rodriguez , G. ( 2003 ). GLS detrending, efficient unit root tests and structural change . Journal of Econometrics 115 : 1 – 27 .[Crossref], [Web of Science ®] , [Google Scholar]) in the presence of additive outliers and breaks are studied by simulation experiments. The results show that the Zivot–Andrews test appears to have size distortions due to the additive outliers whereas the Perron–Rodriguez test exhibits good properties of size and power. However, the two tests are biased when a second break is present but not taken into account. Furthermore, these endogenous break unit root tests tend to determine the break point incorrectly at one period behind the true break point, leading to spurious rejections of the unit root null hypothesis.     

Large Dynamic Covariance Matrices

Second moments of asset returns are important for risk management and portfolio selection. The problem of estimating second moments can be approached from two angles: time series and the cross-section. In time series, the key is to account for conditional heteroscedasticity; a favored model is Dynamic Conditional Correlation (DCC), derived from the ARCH/GARCH family started by Engle (1982). In the cross-section, the key is to correct in-sample biases of sample covariance matrix eigenvalues; a favored model is nonlinear shrinkage, derived from Random Matrix Theory (RMT). The present article marries these two strands of literature to deliver improved estimation of large dynamic covariance matrices. Supplementary material for this article is available online.     

CRIME AND POLICE RESOURCES: THE STREET CRIME INITIATIVE

In this paper we look at the connection between police resources and crime by focussing on a large‐scale policy intervention—the Street Crime Initiative—that was introduced in England and Wales in 2002. This allocated additional resources to some police force areas to specifically target street crime, whereas other forces did not receive any additional funding. Estimates derived from several empirical strategies show that robberies fell significantly in SCI police forces relative to non‐SCI forces after the initiative was introduced. Moreover, the policy seems to have been a cost effective one, even after extensively testing for possible displacement or diffusion effects onto other crimes and into adjacent areas. Overall, we reach the conclusion that increased police resources can be used to generate falls in crime, at least in the context of the SCI program we study. (JEL: H00, H5, K42)     

The Working Families’ Tax Credit and Some European Tax Reforms in A Collective Setting

A framework for simplified implementation of the collective model of labor supply decisions is presented in the context of fiscal reforms in the UK. Through its collective form the model accounts for the well known problem of distribution between wallet and purse, a broadly debated issue which has so far been impossible to model due to the limitations of the unitary model of household behavior. A calibrated data set is used to model the effects of introducing two forms of the Working Families’ Tax Credit. We also summarize results of estimations and calibrations obtained using the same methodology on data from five other European countries. The results underline the importance of taking account of the intrahousehold decision process and suggest that who receives government transfers does matter from the point of view of labor supply and welfare of household members. They also highlight the need for more research into models of household behavior.

Collective Models of Labor Supply with Nonconvex Budget Sets and Nonparticipation: A Calibration Approach

We suggest a methodology to calibrate a collective model with household-specific bargaining rules and marriage-specific preferences that incorporate leisure externalities. The empirical identification relies on the assumption that some aspects of individual preferences remain the same after marriage, so that estimation on single individuals can be used. The procedure maps the complete Pareto frontier of each household in the dataset and we define alternative measures of a power index. The latter is then regressed on relevant bargaining factors, including a set of variables retracing the potential relative contributions of the spouses to household disposable income. In its capacity to handle complex budget sets and labor force participation decisions of both spouses, this framework allows the comparison of unitary and collective predictions of labor supply reactions and welfare changes entailed by fiscal reforms in a realistic setting (see Michal Myck et al., 2006; Denis Beninger et al., 2006).

All agreed: Aumann meets DeGroot

We represent consensus formation processes based on iterated opinion pooling (DeGroot in J Am Stat Assoc 69:118–121, 1974; Lehrer and Wagner in Rational consensus in science and society: a philosophical and mathematical study. Springer, Berlin, 1981) as a dynamic approach to common knowledge of posteriors (Aumann in Ann Stat 4(6):1236–1239, 1976; Geanakoplos and Polemarchakis in J Econ Theory 28:192–200, 1982). We thus provide a concrete and plausible Bayesian rationalization of consensus through iterated pooling. The link clarifies the conditions under which iterated pooling can be rationalized from a Bayesian perspective, and offers an understanding of iterated pooling in terms of higher-order beliefs.     

Semiparametric inference for the recurrent events process by means of a single-index model

In this paper, we introduce new parametric and semiparametric regression techniques for a recurrent event process subject to random right censoring. We develop models for the cumulative mean function and provide asymptotically normal estimators. Our semiparametric model which relies on a single-index assumption can be seen as a dimension reduction technique that, contrary to a fully nonparametric approach, is not stroke by the curse of dimensionality when the number of covariates is high. We discuss data-driven techniques to choose the parameters involved in the estimation procedures and provide a simulation study to support our theoretical results.