A class of adaptive importance sampling weighted EM algorithms for efficient and robust posterior and predictive simulation

A class of adaptive sampling methods is introduced for efficient posterior and predictive simulation. The proposed methods are robust in the sense that they can handle target distributions that exhibit non-elliptical shapes such as multimodality and skewness. The basic method makes use of sequences of importance weighted Expectation Maximization steps in order to efficiently construct a mixture of Student-t$t$ densities that approximates accurately the target distribution–typically a posterior distribution, of which we only require a kernel–in the sense that the Kullback–Leibler divergence between target and mixture is minimized. We label this approach Mixture of  t$t$by Importance Sampling weighted Expectation Maximization (MitISEM). The constructed mixture is used as a candidate density for quick and reliable application of either Importance Sampling (IS) or the Metropolis–Hastings (MH) method. We also introduce three extensions of the basic MitISEM approach. First, we propose a method for applying MitISEM in a sequential manner, so that the candidate distribution for posterior simulation is cleverly updated when new data become available. Our results show that the computational effort reduces enormously, while the quality of the approximation remains almost unchanged. This sequential approach can be combined with a tempering approach, which facilitates the simulation from densities with multiple modes that are far apart. Second, we introduce a permutation-augmented MitISEM approach. This is useful for importance or Metropolis–Hastings sampling from posterior distributions in mixture models without the requirement of imposing identification restrictions on the model’s mixture regimes’ parameters. Third, we propose a partial MitISEM approach, which aims at approximating the joint distribution by estimating a product of marginal and conditional distributions. This division can substantially reduce the dimension of the approximation problem, which facilitates the application of adaptive importance sampling for posterior simulation in more complex models with larger numbers of parameters. Our results indicate that the proposed methods can substantially reduce the computational burden in econometric models like DCC or mixture GARCH models and a mixture instrumental variables model.     

The New Unionism and the New Bargaining Agenda: UNISON–Employer Partnerships on Workplace Learning in Britain

A model of new unionism has been developed which is characterized by features such as the servicing of members as customers and a shift to co‐operative industrial relations. The UNISON–employer partnerships in workplace learning in the UK initially appear to fit such a model. This paper outlines the model of new unionism and cautions against interpreting these partnerships as evidence of its development. The paper concludes that this initiative is organized within a collective framework and may provide a basis for the development of workplace trade union activism rather than being indicative of its decline.     

Securitization: The Transformation of Illiquid Financial Assets into Liquid Capital Market Securities Examples from the European Market

Since the benefits a firm can derive from securitization are universal, the discussion of a market bounded by national borders is somewhat artificial unless the focus is on constraints particular to the country which promote or inhibit the use of securitization. With the exception of the United Kingdom, regulatory constraints have been an important factor in slowing the development of a European market for asset and mortgage backed securities. In addition to the regulatory hurdles, securitization in Europe has been inhibited by segmented corporate bond markets and the relatively slow development of money market savings vehicles for households. Liquidity across credit spectrums has been enhanced since the introduction of the Euro, as has been the competition for savings. European companies are developing the ability to securitize even if the technique is not yet being widely exploited. What is the European market for mortgage and asset backed securities? Does it include the U.S. credit card banks, Citicorp, Chase, MBNA, and First USA that have refinanced U.S. credit card receivables in European currencies and in Euro? Does it include GMAC which has structured Swiss Franc and Euro ABS backed by its U.S. dealer floor plan loans? Does it include Japanese banks that have refinanced Yen denominated leases with Euro and Swiss Franc ABS? Does it include Barclays' issue of $1 billion of ABS backed by sterling credit card receivables? Of course the answer is yes. Markets are defined by both the supply and demand sides. Our analysis focuses on the supply side of the domestic European market.     

Reliability testing of multi-rater feedback

Multirater feedback is an essential part of a seminar concept used by ARAMARK. Before testing the effectiveness of the seminars in terms of learning effects and transfer of training the reliability and validity of multi-rating has to be tested. The conclusion is that trainers are better raters, formative and summative processes and assessments should be separated.     

Build it and they will come: Volunteer opportunities and volunteering

Formal volunteering refers to an individual's unpaid contribution of time to the activities of a charitable or non-profit organization. While the physical presence of these organizations is usually required for citizens who want to volunteer, neighbourhoods vary with respect to the amount of volunteering opportunities available. We are the first to geo-code information on the location of registered charities and the location of individuals, using full six-digit postal codes, to examine how the physical proximity of charities affects the decision to volunteer. We carefully address the possibility that proximity to charities might be endogenous: organizations and volunteers may respond to similar unobservable factors when deciding where to locate. Our results imply that access does matter for the decision to volunteer: one more charity within a 1 km buffer around an individual's residence increases the predicted probability of volunteering by 0.8%. The impact of an additional charity on the likelihood of volunteering decreases with distance from the individual's residence and is more pronounced for urban dwellers, providing further evidence that the location of charities matters when it comes to nudging individuals to volunteer.     

Dynamism and realignment in the HR architecture: Online labor platform ecosystems and the key role of contractors

Given the widespread contribution of independent contractors to organizational innovation and competitive advantage, it is timely to reassess assumptions about the HRM practices appropriate to their management and the rationale for organizations to work with them. In the original and highly influential HR architecture model of Lepak and Snell (1999), contractor status is viewed as an outcome of the low value and/or low uniqueness of human capital resulting in the proposition to externalize and manage them using either none or minimal compliance-based HRM practices. Developments in digital technologies and algorithmic management epitomized by online labor platforms prompt us to reconsider these assumptions and to challenge the proposed links between value/uniqueness of human capital, employment mode and HRM practices that are assumed by the HR architecture model. Using insights from online labor platforms, we argue that the significant benefits to firms of working with contractors, coupled with the possibilities offered by algorithmic management to efficiently monitor and regulate their behavior, provide a compelling reason for organizations to choose external employment modes even when workers are key to value creation. We challenge the alignment and stability of the relationships proposed by the HR architecture model, and offer propositions to extend the model by reconsidering the rationale for, and nature of, HRM practices associated with contractors. This reassessment is both timely and relevant given the growing prominence of business models where externalizing workers is central alongside the development of new forms of algorithmic human resource management to control them.     

Two sides of the same personality coin: An opportunity to refocus (un)ethical analysis

Prior ethics studies highlight the importance of understanding positive or negative leader personality characteristics to improve organizational outcomes. However, few studies combine both positive and negative leader personality characteristics, to unpack and guide ethics theorizations. This lack of methodological balance restricts how we perceive leader ethics, our understandings of organizational experiences, and therefore, our awareness of governance approaches. This study challenges the dominant ethics scholarly orthodoxy—which focuses on positive or negative leader characteristics—by combining self-determination theory and the Dark Triad perspective, to explore the plurality of ethical dimensions within organizational leadership. A case example is provided to highlight the need for this methodological awareness and four avenues of engagement are discussed to improve future organizational governance and ethics scholarship.