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.     

Influencing support of charitable objectives in the near and distant future: delay discounting and the moderating influence of construal level

Two studies investigated the delay discounting effect in charitable giving situations, and whether construal level moderates this effect. In both studies, construal level was manipulated by inducing a concrete vs. an abstract mindset. Participants were asked how much time (Experiment 1) or how much money (Experiment 2) they would be willing to volunteer or donate, respectively, to a self-chosen charitable organization in either the near or distant future. Participants committed themselves to contributing more time and money in the distant than in the near future. Additionally, an abstract (vs. concrete) mindset reduced this delay discounting effect, particularly for monetary donations. Delay discounting of costs associated with altruistic behavior and the role of construal level in increasing donations and volunteering are discussed.     

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.     

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.     

Lower Bounds for the Efficiency of Designs with Respect to the D-Criterion when the Observations are Correlated

In the general linear model consider the experimental design problem for the Gauß-Markov estimator or least squares estimator when the observations are correlated. We prove new formulas for the efficiency of an exact design with respect to the D-criterion. For models with intercept term, for example, these formulas are useful to derive better lower bounds for the efficiency than the bounds recently given for an arbitrary linear model. These bounds are applied in examples to symmetrical regular circulants as covariance matrices. A byproduct of the investigations is some insight as to what kinds of designs might retain their optimality or high efficiency (for the uncorrelated homoscedastic case) under correlated observations.     

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.     

The geographic scale of Metropolitan racial segregation

This article addresses an aspect of racial residential segregation that has been largely ignored in prior work: the issue of geographic scale. In some metropolitan areas, racial groups are segregated over large regions, with predominately white regions, predominately black regions, and so on, whereas in other areas, the separation of racial groups occurs over much shorter distances. Here we develop an approach—featuring the segregation profile and the corresponding macro/micro segregation ratio—that offers a scale-sensitive alternative to standard methodological practice for describing segregation. Using this approach, we measure and describe the geographic scale of racial segregation in the 40 largest U.S. metropolitan areas in 2000. We find considerable heterogeneity in the geographic scale of segregation patterns across both metropolitan areas and racial groups, a heterogeneity that is not evident using conventional “aspatial” segregation measures. Moreover, because the geographic scale of segregation is only modestly correlated with the level of segregation in our sample, we argue that geographic scale represents a distinct dimension of residential segregation. We conclude with a brief discussion of the implications of our findings for investigating the patterns, causes, and consequences of residential segregation at different geographic scales.