Heuristics for single-row layout problems in flexible manufacturing systems

A series of algorithms relevant to one of the commonly used layout schemes in flexible manufacturing systems, that is, the single-row layout, is presented. The algorithms constitute a modified version of a known technique developed for the n m F Fmax sequencing problem. As a result, heuristics are obtained which are easy to implement and which generate good solutions in acceptable response times and outperform other algorithms developed to the same end. An iterative method based on a neighbourhood search is also developed to evaluate the performances in absolute terms.     

Children in Need in the South of Italy: Features and Distortions in the Deinstitutionalisation of Care

Despite the shift in emphasis from institutional to foster family care, in the south of Italy children in need are mainly looked after by residential services. These are required to provide family‐style care and to place children on a short‐term basis. Using data from research on a 100% sample of day units, residential services and children in care in the Calabria region, this article investigates the functioning of the system of care for vulnerable children at the sub‐national level, describes looked‐after children’s characteristics and life conditions and questions the extent to which a real deinstitutionalisation process has occurred in this area. Finally, some deinstitutionalisation recommendations are given.     

What’s so special about Euclidean distance?

In this paper, we provide an application-oriented characterization of a class of distance functions monotonically related to the Euclidean distance in terms of some general properties of distance functions between real-valued vectors. Our analysis hinges upon two fundamental properties of distance functions that we call “value-sensitivity” and “order-sensitivity”. We show how these two general properties, combined with natural monotonicity considerations, lead to characterization results that single out several versions of Euclidean distance from the wide class of separable distance functions. We then discuss and motivate our results in two different and apparently unrelated application areas—mobility measurement and spatial voting theory—and propose our characterization as a test for deciding whether Euclidean distance (or some suitable variant) should be used in your favourite application context. We would like to thank an editor and especially two anonymous referees for very useful comments which helped us to improve the paper substantially.     

INVESTMENT AND TIME TO PLAN AND BUILD: A COMPARISON OF STRUCTURES VS. EQUIPMENT IN A PANEL OF ITALIAN FIRMS

“Time‐to‐build” models of investment expenditures play an important role in many traditional and modern theories of the business cycle, especially for explaining the dynamic propagation of shocks. We estimate the structural parameters of a time‐to‐build model using annual firm‐level investment data on equipment and structures. For expenditures on equipment, we find no evidence of time‐to‐build effects beyond one year. For expenditures on structures, by contrast, there is clear evidence of such effects in the range of two to three years. The contrast between equipment and structures is intuitively reasonable and consistent with previous results. The estimates for structures also indicate that initial‐period expenditures are low and increase as projects near completion. These results provide empirical support for including “time‐to‐plan” effects for investment in structures. More generally, these results suggest a potential source of specification error for Q models of investment and production‐based asset pricing models that ignore the time required to plan, build, and install new capital. (JEL: D24, G31, C33, C34)     

Ranking and Prioritization of Emergency Departments Based on Multi-indicator Systems

In this work we discuss how Emergency Departments (EDs) can be ranked on the basis of multiple indicators. This problem is of absolute relevance due to the increasing importance of EDs in regional healthcare systems and it is also complex as the number of indicators that have been proposed in the literature to measure ED performance is very high. Current literature faces this problem using synthetic (or numerically aggregated) indicators of a set of performance measures but, although simple, this solution has a number of drawbacks that make this choice inefficient: a compensation effect among the indicators; a high degree of subjectivism in the indicators weighting; opacity in the decision making; all the EDs are considered to be comparable. Indeed, the situations in which EDs are comparable (i.e. when all the performance of one ED are not lower than the performance indicators of the other) are a minority and incomparability is by itself a source of information that should be used to identify situations for which different policy actions should be designed. In this work we propose to use non compensatory composite indicators and partial ordering theory to rank and compare EDs giving value to the reasons of such an incomparability. These methods are applied on a case study of 19 EDs in an administrative region in Italy.     

Multidimensional Pigou–Dalton transfers and social evaluation functions

We axiomatize, in the multidimensional case, a social evaluation function that can accommodate a natural Pigou–Dalton principle and correlation increasing majorization. This is performed by building upon a simple class of inframodular functions proposed by Müller and Scarsini under risk.     

Cash‐for‐care payments in Europe: Changes in resource allocation

Resource allocation has been a main policy issue in cash‐for‐care schemes (CfCs) for older people in Europe since their inception. It regards how publicly funded care benefits and services are distributed among older people. The raising pressures of an ageing population and the tensions on the financial sustainability of welfare regimes in place have further exacerbated the relevance of this topic over the recent years. Nevertheless, comparative research so far has overlooked changes in resource allocation in CfCs over time. This article contributes to fill this gap, exploring changes in resource allocation of CfCs for older people in a sample of European countries—Austria, England, France, Germany, Italy, and The Netherlands—since the early '90s (or since the introduction of the scheme). It examines three analytical dimensions: (a) The mix of public services and benefits provided to older people (CfCs, community services in kind, residential care); (b) the level of CfCs coverage; and (c) its generosity. A combined view of these dimensions leads to the discussion of two dilemmas: How to allocate the resources devoted to CfCs in the light of the trade‐off between its coverage and intensity? And, within the whole long‐term care system, how to allocate resources between CfCs and services in kind?     

Work–family conflict and job insecurity: are workers from different generations experiencing true differences?

This paper explores the question whether workers of different generations significantly diverge in their perceptions of work–family conflict and job insecurity and implications of such differences on affective commitment and job satisfaction. Given the explorative nature of this study, we use a multi-method approach which relies on a focus group with Italian graduated students and on a field study with workers from an Italian food processing company respectively grouped in three generational cohorts: Baby Boomers, gen Xers, and Millennials. Overall, our findings demonstrate that workers belonging to different generational cohorts display divergent perceptions of work–family conflict and job insecurity. However, the effects of such perceptions on work attitudes are not directly correlated with the experienced levels of job insecurity and work–family conflict. That is, although Millennials tend to perceive a higher level of job insecurity than Baby Boomers and gen Xers, job insecurity is more likely to produce negative consequences on work attitudes among Baby Boomers and gen Xers rather than among Millennials. Notably, our findings indicate that there are no significant differences with regard to the effects of work–family conflict on affective commitment and job satisfaction among the three generational cohorts considered.     

Uncertainty in Climate Change Modeling: Can Global Sensitivity Analysis Be of Help?

Integrated assessment models offer a crucial support to decisionmakers in climate policy making. For a full understanding and corroboration of model results, analysts ought to identify the exogenous variables that influence the model results the most (key drivers), appraise the relevance of interactions, and the direction of change associated with the simultaneous variation of uncertain variables. We show that such information can be directly extracted from the data set produced by Monte Carlo simulations. Our discussion is guided by the application to the well‐known DICE model of William Nordhaus. The proposed methodology allows analysts to draw robust insights into the dependence of future atmospheric temperature, global emissions, and carbon costs and taxes on the model's exogenous variables.     

Identifying treatment effects using trimmed means when data are missing not at random

Patients often discontinue from a clinical trial because their health condition is not improving or they cannot tolerate the assigned treatment. Consequently, the observed clinical outcomes in the trial are likely better on average than if every patient had completed the trial. If these differences between trial completers and non-completers cannot be explained by the observed data, then the study outcomes are missing not at random (MNAR). One way to overcome this problem—the trimmed means approach for missing data due to study discontinuation—sets missing values as the worst observed outcome and then trims away a fraction of the distribution from each treatment arm before calculating differences in treatment efficacy (Permutt T, Li F. Trimmed means for symptom trials with dropouts. Pharm Stat. 2017;16(1):20–28). In this paper, we derive sufficient and necessary conditions for when this approach can identify the average population treatment effect. Simulation studies show the trimmed means approach's ability to effectively estimate treatment efficacy when data are MNAR and missingness due to study discontinuation is strongly associated with an unfavorable outcome, but trimmed means fail when data are missing at random. If the reasons for study discontinuation in a clinical trial are known, analysts can improve estimates with a combination of multiple imputation and the trimmed means approach when the assumptions of each hold. We compare the methodology to existing approaches using data from a clinical trial for chronic pain. An R package trim implements the method. When the assumptions are justifiable, using trimmed means can help identify treatment effects notwithstanding MNAR data.