Cooperation and preference by peers in early childhood: A longitudinal study

Children who are more proficient in cooperation with peers tend to be more preferred. To date, the development of peer cooperation has been studied mainly in two research traditions, one focusing on action coordination and the other focusing on interaction quality. Both aspects of cooperation are relevant for children's peer relations, but it is unclear whether both aspects of children's earliest cooperation skills predict their later preference by peers after the transition into organized social groups in school. In this study, we assessed coordination proficiency and interaction quality of 181 Dutch children longitudinally from 2 to 4 years of age. No relation between early action coordination and later preference by peers at school was found. However, especially in girls more affiliative and fewer antagonistic behaviors at the age of two predicted likeability among classmates at school at the age of four. The findings shine new light on the earliest foundations of children's peer evaluations.     

Inequality Assessment by Probabilistic Development Indices

Social Indicators Research - This paper analyses the Human Development Index (HDI) time series from 2010 to 2017. An alternative index is studied, which combines the same components of the HDI by...     

Why good practice of OR is not enough—Ethical challenges for the OR practitioner

This paper develops the idea that following rules of good OR practice is necessary, but not sufficient for ethical OR. Several challenges of introducing ethical aspects into OR are discussed, evidencing difficulties and ambiguities in the relationship to be established between the OR practitioner and his/her clients, decision-makers or stakeholders. It shows that neither analysis nor modelling work nor the choice of analytical tools is entirely ethically neutral; incomparability, incommensurability and incertitude must be dealt with. The purpose of this article is to detail several difficulties or dilemmas an OR practitioner may be confronted with in the course of his or her assignment. In such situations, following rules of good practice may not be sufficient to indicate how to act in a morally good way. This paper aims at stimulating reflection by structuring the debate; it may leave the reader unsettled—unsettlement being a result and even aim of many discussions in moral philosophy.     

Pipage Rounding: A New Method of Constructing Algorithms with Proven Performance Guarantee

The paper presents a general method of designing constant-factor approximation algorithms for some discrete optimization problems with assignment-type constraints. The core of the method is a simple deterministic procedure of rounding of linear relaxations (referred to as pipage rounding). With the help of the method we design approximation algorithms with better performance guarantees for some well-known problems including MAXIMUM COVERAGE, MAX CUT with given sizes of parts and some of their generalizations.     

On Approximability of Boolean Formula Minimization

For a Boolean function given by a Boolean formula (or a binary circuit) S we discuss the problem of building a Boolean formula (binary circuit) of minimal size, which computes the function g equivalent to , or -equivalent to , i.e., . In this paper we prove that if P NP then this problem can not be approximated with a good approximation ratio by a polynomial time algorithm.     

Restaurant Revenue Management at Chevys: Determining the Best Table Mix

Revenue management has been used in a variety of industries and generally takes the form of managing demand by manipulating length of customer usage and price. Supply mix is rarely considered, although it can have considerable impact on revenue. In this research, we focused on developing an optimal supply mix, specifically on determining the supply mix that would maximize revenue. We used data from a Chevys restaurant, part of a large chain of Mexican restaurants, in conjunction with a simulation model to evaluate and enumerate all possible supply (table) mixes. Compared to the restaurant's existing table mix, the optimal mix is capable of handling a 30% increase in customer volume without increasing waiting times beyond their original levels. While our study was in a restaurant context, the results of this research are applicable to other service businesses.     

On the correlation between fraud and default risk

Identity fraud is one of the fastest growing white-collar crimes today and a serious concern in our information-based economy. This paper studies one type of identity fraud: new account fraud, where an impostor opens lines of credit using a false identity, made-up or stolen. Relying on a unique data set of consumer bank accounts, that contains information on both, fraud and default losses, I analyze the correlation between fraud and default risk. I find that common socio-economic/demographic account holder characteristics have opposite effects on estimated default and fraud probabilities. For example, women possess a lower fraud probability, but a higher default probability, compared to men, and foreigners are more likely to engage in account fraud but less likely to default than Germans. Also, the portfolio level analysis indicates that portfolio loss distributions are quite sensitive to ex ante portfolio characteristics like the share of foreigners or blue-collar workers. These findings have important implications for banks managing their consumer credit portfolios using limiting rules based on borrower characteristics, and for the adequacy of banks’ capital levels.     

Using Frontier Analysis to Evaluate Company Performance

The measurement of performance is critical to nearly all managerial disciplines. Yet little is known about the aggregation characteristics of the components of performance and how our notion of a ‘good performing firm’ relates to what we use as a dependent variable. In this paper we propose an approach to the measurement of performance that uses the logic of frontier analysis and the technique of data envelopment analysis. The approach is shown to be a reasonable representation of the multidimensional nature of performance and is shown to replicate, effectively, the components that strategic management scholars typically consider when discussing performance. It is also shown to be superior to the simpler alternatives based on traditional approaches to performance measurement.