Predicting future purchases with the Poisson log-normal model

The negative binomial distribution (NBD) has been widely used in marketing for modeling purchase frequency counts, particularly in packaged goods contexts. A key managerially relevant use of this model is Conditional Trend Analysis (CTA)—a method of benchmarking future sales utilizing the NBD conditional expectation. CTA allows brand managers to identify whether the sales change in a second period is accounted for by previous non-, light, or heavy buyers of the brand. Although a useful tool, the conditional prediction of the NBD suffers from a bias: it under predicts what the period-one non-buyer class will do in period two and over predicts the sales contribution of existing buyers. In addition, the NBD's assumption of a gamma-distributed mean purchase rate lacks theoretical support—it is not possible to explain why a gamma distribution should hold. This paper therefore proposes an alternative model using a log-normal distribution in place of the gamma distribution, hence creating a Poisson log-normal (PLN) distribution. The PLN distribution has a stronger theoretical grounding than the NBD as it has a natural interpretation relying on the central limit theorem. Empirical analysis of brands in multiple categories shows that the PLN distribution gives better predictions than the NBD.     

Forecasting interest rates with shifting endpoints

We consider forecasting the term structure of interest rates with the assumption that factors driving the yield curve are stationary around a slowly time‐varying mean or ‘shifting endpoint’. The shifting endpoints are captured using either (i) time series methods (exponential smoothing) or (ii) long‐range survey forecasts of either interest rates or inflation and output growth, or (iii) exponentially smoothed realizations of these macro variables. Allowing for shifting endpoints in yield curve factors provides substantial and significant gains in out‐of‐sample predictive accuracy, relative to stationary and random walk benchmarks. Forecast improvements are largest for long‐maturity interest rates and for long‐horizon forecasts. Copyright © 2013 John Wiley & Sons, Ltd.     

Internationalizing audit education

Audit education is typically offered only to accounting majors. We argue that auditing provides a way of thinking that could serve as a framework for an accounting curriculam. We describe two parts of a course content that could be incorporated into an existing auditing course or a begining accounting course. The first section emphasizes accountability; the second emphasizes the role of the auditor in the accountability process. The concepts are best taught within an international paradigm that permits examination of various institutional environments.     

Shifting models of equality? Union Equality Reps in the public services

This article explores how far the emergence of public sector Equality Representatives represents a departure from a distinct radical model of union self‐organisation generated by the collective mobilisation of politically conscious identities, towards a more inclusive liberal model of equality based on abstract notions of ‘fairness’.     

How universal health care would influence decisions about work and retirement

The current U.S. health care system distorts individual decisions about work and retirement. After a brief explanation of how the current health care system works, this article reviews those distortions and considers how individuals would respond to the implementation of a universal health care system. The author argues that the likely adverse impacts of an employer health insurance mandate on low-skilled workers could be more than offset by a well-designed system of government subsidies.     

Access to credit and informality among micro and small enterprises in Ethiopia

This paper examines the determinants of Micro and Small and Enterprises (MSEs) access to credit in Ethiopia using detailed firm‐level data collected in 2003. Its basic purpose is to identify the various attributes of a firm that determine its access to credit with an emphasis on the role of firm formality. We find that informal firms are more credit constrained compared to formal firms. A firm’s location, membership of a business association and maintaining an accounting record are found to be important determinants of access to credit. Further, we find firms whose owners have vocational training are more credit constrained than those who are not, as are firms that are exclusively male owned. There is no systematic relation between access to credit and a firm’s age, size and the sector in which it operates. The paper concludes with possible policy interventions designed to improve access to credit for MSEs in Ethiopia.     

Abatement and Allocation in the Pilot Phase of the EU ETS

We use historical industrial emissions data to assess the level of abatement and over-allocation that took place across European countries during the pilot phase (2005–2007) of the European Union Emission Trading Scheme. Using a dynamic panel data model, we estimate the counter factual (business-as-usual) emissions scenario for EU member states. Comparing this baseline to allocated and verified emissions, we find that both over-allocation and abatement occurred, along with under-allocation and emissions inflation. Over the three trading years of the pilot phase we find over-allocation of approximately 280 million EUAs and total abatement of 247 Mt CO₂. However, we calculate that emissions inflation of approximately 73 Mt CO₂ also occurred, possibly due to uncertainty about future policy design features.     

Retailing evolution research: Introduction to the special section on retailing research

This JBR Special Issue on Retailing includes several high quality research studies presented at the 10th and 11th Society for Marketing Advances Retail Strategy and Patronage Behavior Symposiums. The articles cover a wide range of interesting and important retailing topics including topics such as atmospherics, self-esteem and advertising. This introduction offers a few comments on the 2007 and 2008 Symposiums' content including a brief overview of each article.