Purchasing performance management systems: an empirical investigation

This article aims at further developing the purchasing performance management systems (PPMSs) body of knowledge, assuming the wider perspective of the adoption process rather than key performance indicators (KPIs) only. In particular, the research questions are focused on understanding what are the most adopted indicators, what are the key elements characterising the implementation process and what are the differences among different organisational levels and different purchasing categories. The literature provides a framework for classifying purchasing KPIs, identifying the implementation process and the PPMS architecture, thus supporting the empirical research protocol. Nine case studies of large multinationals belonging to different industries are conducted. Empirical evidence shows that companies are still adopting mainly an external perspective, by focusing on performance measurement efforts on suppliers. Widely adopted indicators mainly measure cost, time and quality. However, the purchasing department has acquired an important role within the organisation and new performance indicators have been created; flexibility, innovation and sustainability are becoming increasingly important.     

Conditional and predictive probability integral transforms

The conditional probability integral transform, used in goodness-of-fit tests, is compared with its Bayesian counterpart, the predictive probability integral transform, and it is shown that under suitable conditions, in the presence of an adequate group structure, they yield the same transformed random variable, usually uniform on the unit interval.     

Estimability and linearity in normal regression

In the normal regresion model, a relation between the notion of estimability of a distribution and the existence of a linear function of the observations with some desired property is studied. Several definitions of estimability are shown to be equivalent.     

Linking global value chains and supply chain management: evidence from the electric motors industry

The global value chain (GVC) framework and its central concept of governance are increasingly advocated as powerful tools for interpreting managerial issues with particular reference to global supply chain (SC) management. However, a gap still exists about how the GVC concepts, which have been developed at the industry level, can be applied at the company level. The aim of this work is therefore to investigate how the concepts of GVC structure and governance are related to the way the SC is managed. Several research propositions drawn from the literature are investigated by means of seven case studies in the electric motors industry. The results show that the GVC can be a useful framework for understanding and deploying SC management at the company level. Moreover, the analysis of the governance modes provides an effective tool to explain the existing degree of technological and operational collaboration in the SC. Finally, we show the importance of considering such contextual factors as company size and the competitive priorities of the company to move seamlessly between the GVC, at the industry level, and SC management, at the company level.     

Challenging the courtesy bias interpretation of favorable clients' perceptions of family planning delivery

Favorable client perceptions of provider's interpersonal behavior in contraceptive delivery, documented in clinic exit questionnaires, appear to contradict results from qualitative evaluations and are attributed to clients' courtesy bias. In this study, trained simulated clients requested services from Ministry of Health providers in three countries. Providers excelled in courteousness/respect in Peru and Rwanda; in India, providers were less courteous and respectful when the simulated clients chose the pill. Privacy and two-way communication were less prevalent in all three countries. The findings challenge the courtesy bias interpretation. Global results from qualitative studies may have expressed the views of the minority of clients who are not treated well by providers.     

An exact semidefinite programming approach for the max-mean dispersion problem

This paper proposes an exact algorithm for the Max-Mean dispersion problem (\(Max-Mean DP\)), an NP-Hard combinatorial optimization problem whose aim is to select the subset of a set such that the average distance between elements is maximized. The problem admits a natural non-convex quadratic fractional formulation from which a semidefinite programming (SDP) relaxation can be derived. This relaxation can be tightened by means of a cutting plane algorithm which iteratively adds the most violated triangular inequalities. The proposed approach embeds the SDP relaxation and the cutting plane algorithm into a branch and bound framework to solve \(Max-Mean DP\) instances to optimality. Computational experiments show that the proposed method is able to solve to optimality in reasonable time instances with up to 100 elements, outperforming other alternative approaches.     

A comparative assessment of track plates to quantify fine scale variations in the relative abundance of Norway rats in urban slums

Norway rats (Rattus norvegicus) living in urban environments are a critical public health and economic problem, particularly in urban slums where residents are at a higher risk for rat borne diseases, yet convenient methods to quantitatively assess population sizes are lacking. We evaluated track plates as a method to determine rat distribution and relative abundance in a complex urban slum environment by correlating the presence and intensity of rat-specific marks on track plates with findings from rat infestation surveys and trapping of rats to population exhaustion. To integrate the zero-inflated track plate data we developed a two-component mixture model with one binary and one censored continuous component. Track plate mark-intensity was highly correlated with signs of rodent infestation (all coefficients between 0.61 and 0.79 and all p-values?<?0.05). Moreover, the mean level of pre-trapping rat-mark intensity on plates was significantly associated with the number of rats captured subsequently (Odds ratio1.38; 95 % CI 1.19–1.61) and declined significantly following trapping (Odds ratio 0.86; 95 % CI 0.78–0.95). Track plates provided robust proxy measurements of rat abundance and distribution and detected rat presence even when populations appeared ‘trapped out’. Tracking plates are relatively easy and inexpensive methods that can be used to intensively sample settings such as urban slums, where traditional trapping or mark-recapture studies are impossible to implement, and therefore the results can inform and assess the impact of targeted urban rodent control campaigns.     

Quaternary dichotomous voting rules

In this article, we provide a general model of “quaternary” dichotomous voting rules (QVRs), namely, voting rules for making collective dichotomous decisions (to accept or reject a proposal), based on vote profiles in which four options are available to each voter: voting (“yes”, “no”, or “abstaining”) or staying home and not turning out. The model covers most of actual real-world dichotomus rules, where quorums are often required, and some of the extensions considered in the literature. In particular, we address and solve the question of the representability of QVRs by means of weighted rules and extend the notion of “dimension” of a rule.     

Sequential entry in many-to-one matching markets

We study sequential bargaining in many-to-one matching markets. We show that there is an advantage to entering late in the market, and that the last agent to enter the market will receive his or her best partner in a stable matching, extending the results of Blum and Rothblum (J Econ Theory 103(2):429–443, 2002) and Cechlárová (Randomized matching mechanism revisited. Mimeo, Safarik University, 2002) for the marriage model. We also discuss the relation between sequential bargaining and a possible alternative formulation based on the NTU Shapley value. We thank Peter Biró and Utku ünver for their advice on the related literature. We also thank an anonymous referee for comments.