Extending the BG/NBD: A simple model of purchases and complaints

Extant customer-base models like the beta geometric/negative binomial distribution (BG/NBD) predict future purchasing based on customers' observed purchase history. We extend the BG/NBD by adding an important non-transactional element that also drives future purchases: complaint history. Our model retains several desirable properties of the BG/NBD: it can be implemented in readily available software, and estimation requires only customer-specific statistics, rather than detailed transaction-sequence data. The likelihood function is closed-form, and managerially relevant metrics are obtained by drawing from beta and gamma densities and transforming these draws to a sample average. Based on more than two years of individual-level data from a major U.S. internet and catalog retailer, our model with complaints outperforms both the original BG/NBD and a modified version. Even though complaints are rare and non-transactional events, they lead to different substantive insights about customer purchasing and drop-out: customers purchase faster but also drop out much faster. Furthermore, there is more heterogeneity in drop-out rates following a purchase than a complaint.     

The impact of the introduction and use of an informational website on offline customer buying behavior

Do customers increase or decrease their spending in response to the introduction of an informational website? To answer this question, this study considers the effects of the introduction and use of an informational website by a large national retailer on offline customer buying behavior. More specifically, we study a website's effects on the number of shopping trips and the amount spent per category per shopping trip. The model is calibrated through the estimation of a Poisson model (shopping trips) and a type-II tobit model (the amount spent per category per shopping trip), with effect parameters that vary across customers. For the focal retailer, an informational website creates more bad than good news; most website visitors engage in fewer shopping trips and spend less in all product categories. The authors also compare the characteristics of shoppers who exhibit negative website effects with those few shoppers who show positive effects and thus derive key implications for research and practice.     

Candidate gene studies and the quest for the entrepreneurial gene

Candidate gene studies of human behavior are gaining interest in economics and entrepreneurship research. Performing and interpreting these studies is not straightforward because the selection of candidates influences the interpretation of the results. As an example, Nicolaou et al. (Small Bus Econ 36:151?C155, 2011) report a significant association between a common genetic variant in the DRD3 gene and the tendency to be an entrepreneur. We fail to replicate this finding using a much larger, independent dataset. In addition, we discuss the candidate gene approach and give suggestions to avoid the publication of false positives.     

Measuring risky adolescent cycling behaviour

Adolescents are at a greater risk of being involved in traffic accidents than most other age groups, even before they start driving cars. This article aims to determine the factor structure of a self-report questionnaire measuring adolescent risky cycling behaviour, the ACBQ (Adolescent Cycling Behaviour Questionnaire). The questionnaire's structure was based on the widely used Driver Behaviour Questionnaire (DBQ). A sample of secondary school students (N?=?1749; age range: 13-18 years) filled out the questionnaire. Factor analysis revealed a three-factor structure underlying the questionnaire, which was confirmed on two equally large portions of the entire sample. These three underlying factors were identified as errors, common violations and exceptional violations. The ACBQ is a useful instrument for measuring adolescents' risky cycling behaviour.     

Methods and tools for integrated assessment of land use policies on sustainable development in developing countries

For stimulating sustainable development in developing countries, land use patterns and land use changes are considered critical, and therefore effective and efficient land use policies are needed. In this paper we present a methodological framework that has been developed in a joint European and developing countries project (LUPIS – Land Use Policies and Sustainable Development in Developing Countries), to assess the impact of land use policies on sustainable development in developing countries. An illustrative application is presented for a case study in China, where water pollution due to agriculture in Taihu Basin is a major problem.     

Measuring quality performance of cadastral survey and deeds registration work processes

When land parcel boundaries are surveyed for purposes of registration in most southern African countries, the cadastral survey records and diagrams prepared have to be examined and approved by the Surveyor General first before they can be registered in the Deeds Registries. For such records to be approved, their quality must conform to requirements stipulated in relevant acts and regulations. Where regulatory requirements are not met, the records are rejected and returned for corrections and resubmission. From a cross-organizational context, poor quality documents lodged upstream have the effect of congesting examination processes downstream as records are rejected and returned backwards due to quality failure. The paper proposes a quality performance measurement model to analyze quality performance in land administration work processes. The developed model is tested on 2 survey examination and approval sites and 3 deeds registration sites in Namibia, Zimbabwe and South Africa. Based on below expected quality results obtained at one of the sites, a root cause analysis was conducted to establish recurring and underlying causal factors upon which quality improvement strategies can be built on.     

SUSTAINABLE TECHNOLOGY DEVELOPMENT: THE MOBILE HYDROGEN FUEL CELL

Sustainable technology development implies large changes in technological systems. The illustrative process ‘hydrogen fuel cell in a boat’ is used here as an example of a learning process concerning a transition towards a hydrogen economy. Theoretically the concepts of constructive technology assessment, back-casting and social niche management are combined in this approach.     

Regime switching as a test for exchange rate bubbles

This paper develops a new test for speculative bubbles, which is applied to data for the Japanese yen, the German mark and the Canadian dollar exchange rates from 1977 to 1991. The test assumes that bubbles display a particular kind of regime-switching behaviour, which is shown to imply coefficient restrictions on a simple switching-regression model of exchange rate innovations. Test results are sensitive to the specification of exchange rate fundamentals and other factors. Evidence most consistent with the bubble hypothesis is found using an overshooting model of the Canadian dollar and a PPP model of the Japanese yen.     

A REVISED GEOMETRY OF MEAN-VARIANCE EFFICIENT PORTFOLIOS

A revised definition of efficiency compares portfolios with different net worths. One axiom rules out instantaneous riskless gains, the other asserts that it costs money to buy good portfolios. Unlimited short sales are allowed. Portfolios which cannot be improved at any price are called absolutely efficient. The geometry of the mean-standard deviation frontiers is governed by three “efficient set constants”. A few results regarding efficient portfolios must be modified, and a new version of the security line equation is proposed. Explicit formulas are given: no need to use different formulas for singular or non-singular covariance matrix.