The Likelihood of Choosing the Borda-Winner With Partial Preference Rankings of the Electorate

Given that n voters report only the first r (1 ≤ r \u3c m) ranks of their linear preference rankings over m alternatives, the likelihood of implementing Borda outcome is investigated. The information contained in the first r ranks is aggregated through a Borda-like method, namely the r-Borda rule. Monte-Carlo simulations are run to detect changes in the likelihood of r-Borda winner(s) to coincide with the original Borda winner(s) as a function of m, n and r. The voters’ preferences are generated through the Impartial Anonymous and Neutral Culture Model, where both the names of the alternatives and voters are immaterial. It is observed that, for a given r, the likelihood of choosing the Borda winner decreases down to zero independent of n as m increases within the computed range of parameter values, 1≤ m, n ≤ 30. For n = 30, this likelihood is given as an approximating function of r and m through least square fit method

Weakening organizational ties? A classification of styles of volunteering in the Flemish red cross

This article presents an initial empirical assessment of a new analytical framework of styles of volunteering (SOV). The framework suggests that volunteering can be categorized in terms of a multidimensional set of cultural and structural indicators that cohere in systematic and varying ways. With data drawn from a survey of 652 Flemish Red Cross volunteers, a multivariate analysis reveals five different SOV categories of volunteers: episodic contributors, established administrators, reliable coworkers, service-oriented core volunteers, and critical key figures. The research findings indicate that the volunteer reality is far more complex than suggested by conventional approaches to the study of volunteering

Impossibility theorems involving weakenings of expansion consistency and resoluteness in voting

A fundamental principle of individual rational choice is Sen's $\gamma$ axiom, also known as expansion consistency, stating that any alternative chosen from each of two menus must be chosen from the union of the menus. Expansion consistency can also be formulated in the setting of social choice. In voting theory, it states that any candidate chosen from two fields of candidates must be chosen from the combined field of candidates. An important special case of the axiom is binary expansion consistency, which states that any candidate chosen from an initial field of candidates and chosen in a head-to-head match with a new candidate must also be chosen when the new candidate is added to the field, thereby ruling out spoiler effects. In this paper, we study the tension between this weakening of expansion consistency and weakenings of resoluteness, an axiom demanding the choice of a single candidate in any election. As is well known, resoluteness is inconsistent with basic fairness conditions on social choice, namely anonymity and neutrality. Here we prove that even significant weakenings of resoluteness, which are consistent with anonymity and neutrality, are inconsistent with binary expansion consistency. The proofs make use of SAT solving, with the correctness of a SAT encoding formally verified in the Lean Theorem Prover, as well as a strategy for generalizing impossibility theorems obtained for special types of voting methods (namely majoritarian and pairwise voting methods) to impossibility theorems for arbitrary voting methods. This proof strategy may be of independent interest for its potential applicability to other impossibility theorems in social choice.Comment: Forthcoming in Mathematical Analyses of Decisions, Voting, and Games, eds. M. A. Jones, D. McCune, and J. Wilson, Contemporary Mathematics, American Mathematical Society, 202

Recommender systems in industrial contexts

This thesis consists of four parts: - An analysis of the core functions and the prerequisites for recommender systems in an industrial context: we identify four core functions for recommendation systems: Help do Decide, Help to Compare, Help to Explore, Help to Discover. The implementation of these functions has implications for the choices at the heart of algorithmic recommender systems. - A state of the art, which deals with the main techniques used in automated recommendation system: the two most commonly used algorithmic methods, the K-Nearest-Neighbor methods (KNN) and the fast factorization methods are detailed. The state of the art presents also purely content-based methods, hybridization techniques, and the classical performance metrics used to evaluate the recommender systems. This state of the art then gives an overview of several systems, both from academia and industry (Amazon, Google ...). - An analysis of the performances and implications of a recommendation system developed during this thesis: this system, Reperio, is a hybrid recommender engine using KNN methods. We study the performance of the KNN methods, including the impact of similarity functions used. Then we study the performance of the KNN method in critical uses cases in cold start situation. - A methodology for analyzing the performance of recommender systems in industrial context: this methodology assesses the added value of algorithmic strategies and recommendation systems according to its core functions.Comment: version 3.30, May 201

Micro simulations on the effects of ageing-related policy measures: The Social Affairs Department of the Netherlands Ageing and Pensions Model

his paper describes a newly extended version of the dynamic micro simulation model SADNAP (Social Affairs Department of the Netherlands Ageing and Pensions model). SADNAP is being developed for calculating the financial and economic implications of the ageing of the population and of the ageing-related policy measures that are being proposed to cope with ageing. The model uses administrative datasets of Dutch public pension payments and entitlements for both public and private pensions. SADNAP has already been in use since 2007 for forecasting the state pension expenditures and for analysing the budgetary effects of policy changes. The model has been extended in order to give a broader assessment of policy alternatives by providing insight into other important evaluation indicators like income redistribution and the retirement decision of workers. For the modelling of income redistribution a new micro data source with individual data on private pensions is combined with differentiation of mortality rates in order to gain a better insight in the income at the individual level within the population of pensioners. For the modelling of the retirement decision an option value model is developed in which key parameters vary at the individual level in order to benefit from the micro simulation approach. These extensions greatly enhance the performance of SADNAP. Besides the financial implications, additional insight can now be provided into the effects of policy measures on a set of key indicators. In this paper both extensions are described in detail and a complete baseline projection of all key indicators is discussed.Microsimulation, ageing, pensions, retirement