Bayesian Forecasting of Many Count-Valued Time Series

Abstract

We develop and exemplify application of new classes of dynamic models for time series of nonnegative counts. Our novel univariate models combine dynamic generalized linear models for binary and conditionally Poisson time series, with dynamic random effects for over-dispersion. These models estimate dynamic regression coefficients in both binary and nonzero count components. Sequential Bayesian analysis allows fast, parallel analysis of sets of decoupled time series. New multivariate models then enable information sharing in contexts when data at a more highly aggregated level provide more incisive inferences on shared patterns such as trends and seasonality. A novel multiscale approach—one new example of the concept of decouple/recouple in time series—enables information sharing across series. This incorporates cross-series linkages while insulating parallel estimation of univariate models, and hence enables scalability in the number of series. The major motivating context is supermarket sales forecasting. Detailed examples drawn from a case study in multistep forecasting of sales of a number of related items showcase forecasting of multiple series, with discussion of forecast accuracy metrics, comparisons with existing methods, and broader questions of probabilistic forecast assessment.     

Private equity: A review and synthesis

The recent international surge in private equity markets has been accompanied by growing interest in its nature and effects. Private equity involves investment in unquoted companies and includes both early stage venture capital and later stage buyouts. The latter, which have been particularly controversial, are our focus. This paper provides a review of the different theoretical approaches that have been deployed to understand this phenomenon. Thereafter, the findings of a large cross section of empirical studies within a range of different national settings are compared and contrasted. Finally, existing themes emerging from – and gaps in – the existing literature and likely future directions are summarized.     

Coalmining and the National Scheme for Disabled Ex-Servicemen after the First World War

After the First World War, disabled British veterans returned home to an uncertain future of work. In addition to voluntary efforts, the government’s response to the national employment crisis – the National Scheme for Disabled Ex-Servicemen (commonly known as the King’s Roll) – was established in 1919 to encourage employers to hire a five per cent quota of disabled ex-servicemen. Historians have recently revisited the scheme, noting that in many cases the process was slow and fraught, with many disabled veterans facing the prospect of unemployment, yet few have paid attention to soldiers’ pre-war working backgrounds and the specific requests of British industries. This article focuses on British coalminers returning from war. What role was there in this national situation for an industry known for its own high rate of accident and injury? Although the King’s Roll made some attempt to find veterans specifically targeted jobs above and below ground according to their impairments, it proved unable to incorporate coalmining. Instead, many disabled ex-servicemen returned to the workplace and utilized their existing identities as miners to navigate the process. With the industry beginning to decline, many faced potential regression in job status, exploitation or unemployment. By shifting to an industry-specific focus, this case study explores the contested nature of work for disabled people after the First World War, and highlights the interrelation and importance of workplace identity for the returning disabled veteran.     

Brexit,Private Equity and Management

We analyse the expected impact of Brexit on private equity and its implications for management research. Specifically, we explore the implications for private equity funds and funding, and at the portfolio firm level with respect to employment and performance.     

Hybrid Strategies: Allocating Involvement in the Digital Age

An important trait of mobile phones is their capacity to superimpose multiple social interactions in time and space. Little research examines how individuals choose between face‐to‐face and digitally mediated interactions in specific social contexts. Drawing upon focus group interviews with a diverse sample of university students in the United States, we argue that, contrary to a perspective that is popular in theory and journalistic commentary, mobile phone users do not experience the digital and the face‐to‐face as distinct realms. In deciding where to direct their attention, users enmesh the distant and the present, making moves that are expressive and strategic in their own right that reveal the interest, intimacy and urgency that users place in multiple, coinciding social involvements.     

An Inductive Analysis of Young Adults’ Conceptions of Femininity and Masculinity and Comparison to Established Gender Inventories

This study provides an analysis of the content of feminine and masculine characteristics/behaviors described in writing by 366 young women and 289 young men from the U.S. Emergent characteristics/behaviors were placed into domains. For both femininity and masculinity, the domains of “physical differences related to sex” and “emphasized physical differences” emerged. For masculinity, additional domains were: “activities and interests focused on the body,” “powerful or oriented toward power,” and “emotion-control or emotionally-limited.” For femininity, additional domains were “lacking power,” “orientation to other people,” and “emotional.” We then compared the characteristics/behaviors and domains we discovered to gender inventories that are commonly used in the contemporary period. The masculine domains focused on physical differences, activities, and interests that emerged from the present study are mostly absent from these masculinity inventories. The domains focused on power and restricted emotion are evident in these inventories, but these inventories do not cover all of the characteristics within our domains. The feminine domains that emerged from the present study are more often covered in these inventories, but some of the specific feminine characteristics we found are not evident in these inventories. Results are discussed in terms of gender role theory, gender inequality, and potential application for qualitative and quantitative inquiries into the construction of gender.     

Statistical analysis of an endemic disease from a capture–recapture experiment

There are a number of statistical techniques for analysing epidemic outbreaks. However, many diseases are endemic within populations and the analysis of such diseases is complicated by changing population demography. Motivated by the spread of cowpox amongst rodent populations, a combined mathematical model for population and disease dynamics is introduced. A Markov chain Monte Carlo algorithm is then constructed to make statistical inference for the model based on data being obtained from a capture–recapture experiment. The statistical analysis is used to identify the key elements in the spread of the cowpox virus.     

‘Egypt in transition’: uniting service-learning and short-term study-abroad

Study-abroad has become a popular method for promoting international education in university curricula. Yet, with today’s growing non-traditional student who is older, working, and increasingly a member of a racial/ethnic minority group, traditional study-abroad programmes of a semester or year abroad have become more problematic, if not impossible. The paradigm of short-term study-abroad, combined with a service-learning pedagogy, expands the opportunities for non-traditional students to have an international educational experience. This dual approach is applied to a study-abroad course in Egypt, using a ‘Service-Learning Cross-Cultural Research’ pedagogy. Data from student participants in our programme (based on qualitative data from student reflection papers, focus group interviews and student discussions) indicate an expanded global awareness, changed career goals and greater appreciation for cross-cultural dialogue.