A multivariate Poisson mixture model for marketing applications

This paper describes a multivariate Poisson mixture model for clustering supermarket shoppers based on their purchase frequency in a set of product categories. The multivariate nature of the model accounts for cross-selling effects between the purchases made in different product categories. However, for computational reasons, most multivariate approaches limit the covariance structure by including just one common interaction term, or by not including any covariance at all. Although this reduces the number of parameters significantly, it is often too simplistic as typically multiple interactions exist on different levels. This paper proposes a theoretically more complete variance/covariance structure of the multivariate Poisson model, based on domain knowledge or preliminary statistical analysis of significant purchase interaction effects in the data. Consequently, the model does not contain more parameters than necessary, whilst still accounting for the existing covariance in the data. Practically, retail category managers can use the model to devise customized merchandising strategies.     

西方现代股利政策理论及实证研究回顾

本文对西方现代公司股利政策方面的理论和实证研究进行了一个综合性的回顾和分析。其中包括主流的股利行为模型、股利的信息内涵、代理成本、追随者效应,也包括国内研究中较少涉及的债务约束、声誉学说、成长机会和交易成本问题,以期对国内相对落后的股利政策研究和随意性较强的股利政策制定带来一定的借鉴意义。     

Nonlinear models with panel data

Panel data play an important role in empirical economics. With panel data one can answer questions about microeconomic dynamic behavior that could not be answered with cross sectional data. Panel data techniques are also useful for analyzing cross sectional data with grouping. This paper discusses some issues related to specification and estimation of nonlinear models using panel data.JEL Classification: C230The research behind this paper was supported by the National Science Foundation, the Gregory C. Chow Econometric Research Program at Princeton University, and Danish National Research Foundation (through CAM at the University of Copenhagen). The author thanks Ekaterini Kyriazidou, Hong Li, Marina Sallustro, and the editors for helpful suggestions.     

产品目标用户群划分方法研究

随着产业信息化的不断深入,产品进入快速更迭阶段,这源于用户群对产品的需求处于实时变化的状态。"以用户为中心"设计理念成为左右产品亲和度的首要标准。传统的产品用户群划分方法已经随着时间不断得到修正和补充。本文通过以用户需求为主要划分维度,研究用户数据提取优先级,构建典型目标用户群模型的方式动态研究产品整个阶段目标用户群的划分。     

Why do statistics journals have low impact factors?

In this paper, we answer the question why statistics journals get lower impact factors than journals in other disciplines. We analyze diffusion patterns of papers in several journals in various academic fields. To obtain insights into the diffusion of the citation counts of the papers, the data are analysed with the Bass model, leading to values for the time-to-peak that can be used to compare the speeds of diffusion paper citations of the different disciplines. Estimation results show that for statistics journals, it takes significantly more years to reach their peak. To further investigate diffusion, we also compute the percentages of the total number of citations a paper has after 2 or 3 years. Again, it appears that statistics journals have slower citation diffusion than journals in other disciplines. We conclude with some suggestions to reduce this disparity.     

Estimating structural equation models with non-normal variables by using transformations

We discuss structural equation models for non-normal variables. In this situation the maximum likelihood and the generalized least-squares estimates of the model parameters can give incorrect estimates of the standard errors and the associated goodness-of-fit chi-squared statistics. If the sample size is not large, for instance smaller than about 1000, asymptotic distribution-free estimation methods are also not applicable. This paper assumes that the observed variables are transformed to normally distributed variables. The non-normally distributed variables are transformed with a Box–Cox function. Estimation of the model parameters and the transformation parameters is done by the maximum likelihood method. Furthermore, the test statistics (i.e. standard deviations) of these parameters are derived. This makes it possible to show the importance of the transformations. Finally, an empirical example is presented.     

Inference on endogenously censored regression models using conditional moment inequalities

Under a quantile restriction, randomly censored regression models can be written in terms of conditional moment inequalities. We study the identified features of these moment inequalities with respect to the regression parameters where we allow for covariate dependent censoring, endogenous censoring and endogenous regressors. These inequalities restrict the parameters to a set. We show regular point identification can be achieved under a set of interpretable sufficient conditions. We then provide a simple way to convert conditional moment inequalities into unconditional ones while preserving the informational content. Our method obviates the need for nonparametric estimation, which would require the selection of smoothing parameters and trimming procedures. Without the point identification conditions, our objective function can be used to do inference on the partially identified parameter. Maintaining the point identification conditions, we propose a quantile minimum distance estimator which converges at the parametric rate to the parameter vector of interest, and has an asymptotically normal distribution. A small scale simulation study and an application using drug relapse data demonstrate satisfactory finite sample performance.     

Can inflation targeting reduce price information asymmetry and alleviate corruptive behavior? Evidence from developing countries

This paper examines the role of inflation targeting as a price signaling mechanism reducing price information asymmetry and potentially reducing incentives for corruptive actions through its direct control on the inflation rate, thus simultaneously increasing institutional quality. The obtained evidence suggests that adopting inflation targeting lowers corruption in a sample of 61 developing countries for the period between 1990 and 2018. Countries that have adopted inflation targeting experience lower corruption levels, as measured by the corruption perceptions (CP) index, controlling for other relevant determinants of corruption identified in the empirical literature, such as inflation, level of income, income distribution, trade openness and the rule of law. This result is sensitive to the type of inflation targeting adopted. Soft (unofficial) inflation targeting has no significant effect on the corruption level, giving support to the claim that strong institutional commitment, accompanied by transparency and constant communication with regards to inflation targets by the central bank, provides an adequate price signaling mechanism. In addition, the analysis provides evidence that an efficient rule of law reduces corruption levels significantly, although its effects are rather modest to support the claims that it can solely lessen corruptive behavior in the sample of developing countries.     

Notes on contributors

This article establishes a basic framework for a comparative analysis of public management reform around the world in recent times. It focuses on politicians and administrators as ‘drivers’ and/or ‘supporters’ of reform, as influenced by their policy roles and contributions, along with electoral politics and government-legislature alignments. Three models are outlined on the basis of the reform experience of selected countries. The models are then related to various reform initiatives by way of eight propositions. The underlying aim is to provide some guidance for research and understanding of reform in different contexts.     

The Impact of the EU–US Open Skies Agreement and the Resulting British Airway's Open Skies Initiative: Passenger Numbers in London,Amsterdam and Paris

Abstract

The advent of the EU–US Open Skies Agreement has been widely anticipated. A number of consequences have been predicted, for example, impacts on fares, passenger volumes, choice and consumer welfare. Airline costs are also predicted to fall as a result of increased competitiveness and increased cooperation among airlines. For the short period since the implementation of the Agreement, it is relatively easy to assess the supply-side changes that have been made, but more difficult to make wider judgements. This paper indicates the data that will be required to make these judgements and notes some methodological difficulties. Early estimates of the impact on passenger numbers are given using time series analysis focusing on London airports, in particular London Heathrow and airports served by British Airway's Open Skies Airline from Paris Orly and Amsterdam Schipol.

Impact de l'accord Ciel Ouvert entre l'UE et les États-Unis et de l'initiative Open Skies résultante de British Airways: nombre de passagers à Londres, Amsterdam et Paris

Résumé L'avènement de l'accord Ciel ouvert entre l'UE et les États-Unis avait été très largement prévu, et on a prédit un certain nombre de conséquences, notamment l'impact sur le prix des billets, sur les volumes de passagers, sur le choix pour les consommateurs et sur leur bien-être, entre autres. On prévoit également que les coûts des compagnies d'aviation devraient baisser, en conséquence de l'augmentation non seulement de la compétitivité, mais aussi de la concurrence entre les compagnies. A l'issue de la courte période qui s'est écoulée depuis l'implémentation de l'Accord, il est relativement aisé d’évaluer les variations qui se sont produites du côté de l'offre, mais beaucoup plus difficile de formuler des opinions plus générales. La présente communication indique les données qui seront requises pour formuler ces jugements, et souligne certaines difficultés sur le plan de la méthodologie. Des premières évaluations de l'impact sur le nombre de voyageurs ont été avancées, sur la base d'analyses à série temporelle concentrées sur les aéroports de Londres, notamment l'aéroport Heathrow de Londres et les aéroports desservis par la compagnie Open Skies de British Airway entre Paris Orly et l'aéroport Schipol d'Amsterdam.

El efecto del Acuerdo de Cielos abiertos entre la UE y EE.UU. y el resultado de la Iniciativa de Cielos abiertos de British Airways: número de pasajeros en Londres, Ámsterdam y París

Resumen El advenimiento del Acuerdo de Cielos abiertos entre la EU y EE.UU. era algo ampliamente esperado. Se han pronosticado muchas consecuencias, por ejemplo, los efectos sobre las tarifas, los volúmenes de pasajeros, las opciones y el bienestar de los consumidores. También se ha pronosticado la caída de los costes de las aerolíneas debido a una mayor competitividad y el incremento de la cooperación entre las aerolíneas. En el corto periodo de implantación del Acuerdo, es relativamente fácil evaluar los cambios que se han dado en el lado de la oferta, sin embargo, es más difícil realizar estimaciones mayores. Este trabajo indica que se necesitan datos para realizar estas estimaciones y hace referencia a algunas dificultades metodológicas. Los primeros estimativos del efecto sobre los números de pasajeros se han obtenido mediante análisis de series de tiempo centrados en los aeropuertos de Londres, en particular, el de Heathrow, y en los aeropuertos atendidos por la Aerolínea de Cielos abiertos de British Airways de Orly, en París, y Schipol, en Ámsterdam.