Procurement process: Decision by exclusion and pairwise comparisons

Two case studies illustrate multicriteria decision making techniques frequently used in procurement practice: least-cost sufficient performance and weighted utility optimization. Both techniques have defects and are rarely robust. Decision by exclusion and pairwise comparisons is proposed as a third approach which eliminates inferior alternatives by generalized forms of minimum performance requirements established under multicriteria framework. It is more robust and maintains high level of accountability.     

The simulation of industrial robot systems

This paper describes the GRASP computer aided design system for modelling and evaluating industrial robot workplaces. GRASP satisfies a range of simulation needs within the context of designing, implementing and operating industrial robotic systems. The GRASP software may be used to investigate robots operating by themselves or, more likely, as part of an integrated cell. Facilities within GRASP assist workplace layout, position and velocity evaluations, clash detection and co-ordination between items. A robot library exists and is being extended, and an embryo off-line programming facility has been used under restricted conditions. GRASP has been used to help solve a wide range of practical industrial robot problems and has proved itself technically, and also as an educational tool, by showing how a proposed system would operate. The paper describes the facilities within GRASP.     

Changing Policy Environments in Europe and the Resilience of the Third Sector

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations - In the article, we analyse the impact of changing policy environments on the development of the third sector in Europe....     

How do we capture 15 years of complex and meaningful data about young people's lives?

Abstract

This paper describes the development of a method of data collection, which captures the complexity of living situations, family dynamics and key life events of teenagers. This ‘Life History Calendar’ was adapted from earlier life history calendar methods for a multidisciplinary intergenerational study. The new calendar is able to record details of 15 years of teenage participants’ lives and can be administered to teenagers and their parents to show changes over individual lives and difference between individuals in a cohort. Referring to some preliminary data, we show that the calendar is a practical and effective method of data collection, which will be useful to researchers and practitioners working with young people and their families.     

Block unimodality for multivariate Bayesian robustness

Summary The development of Bayesian robustness has been growing in the last decade. The theory has extensively dealt with the univariate parameter case. Among the vast amount of proposals in the literature, only a few of them have a straightforward extension to the multivariate case. In this paper we consider the multidimensional version of the class of ε-contaminated prior distributions, with unimodal contaminations. In the multivariate case there is not a unique definition of unimodality and one's choice must be based on statistical ground. Here we propose the use of the block unimodal distributions, which proved to be very suitable for modelling situations where the coordinates of the parameter ϑ are deemed, a priori, weakly correlated.     

Unified Bayesian conditional autoregressive risk measures using the skew exponential power distribution

Statistical Methods & Applications - Conditional Autoregressive Value-at-Risk and Conditional Autoregressive Expectile have become two popular approaches for direct measurement of market risk....     

Censored Exponential Data: Large Deviations for MLEs and Posterior Distributions

In this article, we consider several statistical models for censored exponential data. We prove a large deviation result for the maximum likelihood estimators (MLEs) of each model, and a unique result for the posterior distributions which works well for all the cases. Finally, comparing the large deviation rate functions for MLEs and posterior distributions, we show that a typical feature fails for one model; moreover, we illustrate the relation between this fact and a well-known result for curved exponential models.     

Bayesian binary quantile regression for the analysis of Bachelor-to-Master transition

The multi-cycle organization of modern university systems stimulates the interest in studying the progression to higher level degree courses during the academic career. In particular, after the achievement of the first level qualification (Bachelor degree), students have to decide whether to continue their university studies, by enrolling in a second level (Master) programme, or to conclude their training experience. In this work we propose a binary quantile regression (BQR) approach to analyse the Bachelor-to-Master transition phenomenon with the adoption of the Bayesian inferential perspective. In addition to the traditional predictors of academic outcomes, such as the personal characteristics and the field of study, different aspects of student's performance are considered. Moreover, the role of a new contextual variable, representing the type of university regulations experienced during the academic path, is investigated. The utility of the Bayesian BQR to characterize the non-continuation decision after the first cycle studies is illustrated with an application to administrative data of Bachelor graduates at the School of Economics of Sapienza University of Rome. The method favourably compares with more conventional model specifications concerning the conditional mean of the binary response.     

Precaution and liquidity in the demand for housing

We exploit cross-sectional mortgage data to investigate the importance of liquidity constraints and a precautionary motive in the demand for housing. Households that are not liquidity constrained consume housing services essentially as the life cycle hypothesis suggests but with a significant precautionary component. Households that are liquidity constrained, in terms of not meeting standard loan-to-value or payments-to-income constraints, are similar to unconstrained households in most respects, including the precautionary motive, but they respond somewhat less to fluctuations in their lifetime income - suggesting some influence of bank-induced liquidity constraints. We additionally find, however, that banks enforce liquidity constraints only weakly.