Chance theory: A separation of riskless and risky utility

Journal of Risk and Uncertainty - In a temporal context, sure outcomes may yield higher utility than risky ones as they are available for the execution of plans before the resolution of...     

Design effect of randomized systematic sampling

In statistical practice, systematic sampling (SYS) is used in many modifications due to its simple handling. In addition, SYS may provide efficiency gains if it is well adjusted to the structure of the population under study. However, if SYS is based on an inappropriate picture of the population a high decrease of efficiency, i.e. a high increase in variance may result by changing from simple random sampling to SYS. In the context of two-stage designs SYS so far seems often in use for subsampling within the primary units. As an alternative to this practice, we propose to randomize the order of the primary units, then to select systematically a number of primary units and, thereafter, to draw secondary units by simple random sampling without replacement within the primary units selected. This procedure is more efficient than simple random sampling with replacement from the whole population of all secondary units, i.e. the variance of an adequate estimator for a total is never increased by changing from simple random sampling to randomized SYS whatever be the values associated by a characteristic with the secondary units, while there are values for which the variance decreases for the change mentioned. This result should hold generally, even if our proof, so far, is not complete for general sample sizes.     

Experience with corporate simulation models—A survey

In this article the authors argue that if corporate simulation models are going to help management meet their objectives then changes are necessary. These changes require that (i) the models should be more user oriented, (ii) there should be more emphasis on production modelling, (iii) there will be an increased use of optimization techniques linked to corporate models, (iv) there will be an increased effort to integrate finance, marketing and production, (v) the more sophisticated application will be concerned with the external environment and (vi) model builders should become more aware of the importance of corporate politics.     

Rational Migration Policy Should Tolerate Non-zero Illegal Migration Flows: Lessons from Modelling the Market for Illegal Migration

The debate on the immigration policies in OECD countries has turned its attention towards illegal migrants. Given that migration flows are determined by immigration laws, the probability of potential detection, penalties for unauthorized migrants and their employers, and income differences between sending and receiving countries, this paper presents a new approach to the problem of illegal migration, grounded on the economic theory of illegal behaviour. The framework considers the interaction of potential migrants, citizens, employers, and the government. After introducing the supply function of illegal migration and its determinants, the trade-off between social costs and benefits of preventing and combating illegal migration is demonstrated. This trade-off results in an optimal level of migration larger than zero. A complete "market model" of illegal migration is offered by presentation of a demand curve of illegal migration, based on the tolerance of the society towards clandestine foreigners. Equilibrium forces predict a non-zero level of illegal migration. The rule of law of our legal systems, according to which any illegal activity has to be reduced to zero, bears the danger of producing inefficient disequilibria. A reasonable policy of wanted and unwanted migration should address the question of how to allocate scarce resources. Ignoring social optima and equilibrium forces means to abandon public resources that could be used for other public assignments, such as schooling or foreign aid, for instance, i.e., measures that could strike the problem of illegal migration at its root.     

Making a difference in Mogadishu? Experiences of multi-sited embeddedness among diaspora youth

ABSTRACT

Civic participation today is increasingly multi-sited, operating in, between and across specific locations. Growing numbers of people experience multi-sited embeddedness, which I understand both in the sense of belonging to and engaging in multiple communities. In this article, I focus on those who left Somalia as young children or were born to Somali parents in exile, and ask what motivates these young people to return or turn to the Somali region. What experiences shape their civic engagement and where do they engage? How does their hybrid, multi-sited or embedded sense of identity impact their engagement in several locations? And how does that engagement affect their sense of identity? The article is based on 80 in-depth interviews and four focus group discussions in Garowe, Hargeisa, Mogadishu, Oslo and the Twin Cities. Informants stayed for shorter or longer durations in the Somali region but lived for the larger part of their lives in Norway or the United States. I illustrate how young people’s civic engagement impact feelings of belonging as much as their sense of belonging influences their civic actions. In this article, I argue for non-binary ways of studying multi-sited embeddedness that do justice to diaspora youth’s everyday negotiations.     

How Friendship Network Characteristics Influence Subjective Well-Being

This article explores how friendship network characteristics influence subjective well-being (SWB). Using data from the 2003 General Social Survey of Canada, three components of the friendship network are differentiated: number of friends, frequency of contact, and heterogeneity of friends. We argue that these characteristics shape SWB through the benefits they bring. Benefits considered are more social trust, less stress, better health, and more social support. Results confirm that higher frequency of contacts and higher number of friends, as well as lower heterogeneity of the friendship network are related to more social trust, less stress, and a better health. Frequency of contact and number of friends, as well as more heterogeneity of the friendship network increase the chance of receiving help from friends. With the exception of receiving help from friends, these benefits are in turn related to higher levels of SWB. Only the frequency of meeting friends face-to-face has a remaining positive direct influence on SWB.     

Capacity inverse minimum cost flow problem

Given a directed graph G=(N,A) with arc capacities u _ij and a minimum cost flow problem defined on G, the capacity inverse minimum cost flow problem is to find a new capacity vector [^(u)]\hat{u} for the arc set A such that a given feasible flow [^(x)]\hat{x} is optimal with respect to the modified capacities. Among all capacity vectors [^(u)]\hat{u} satisfying this condition, we would like to find one with minimum ||[^(u)]-u||\|\hat{u}-u\| value. We consider two distance measures for ||[^(u)]-u||\|\hat{u}-u\| , rectilinear (L ₁) and Chebyshev (L _∞) distances. By reduction from the feedback arc set problem we show that the capacity inverse minimum cost flow problem is NP\mathcal{NP} -hard in the rectilinear case. On the other hand, it is polynomially solvable by a greedy algorithm for the Chebyshev norm. In the latter case we propose a heuristic for the bicriteria problem, where we minimize among all optimal solutions the number of affected arcs. We also present computational results for this heuristic.     

Some Extensions of Domain Criteria in Decision Making under Uncertainty*

This paper examines some approaches to decision problems under uncertainty. Starr's [29] domain criterion is presented and modified to take into account different philosophies concerning the desirability of winning versus the importance of avoiding losses. The concept of expected value of distribution information is defined and its computation is illustrated with a numerical example. Target values are then introduced into the model and a parametric procedure is used to maximize the chances of achieving a certain level of the given objective. Finally, we show how the concepts developed in this paper might provide further insight into some decision situations reported in the literature.