Using Hit Rates to Test for Racial Bias in Law Enforcement: Vehicle Searches in Wichita

This paper considers the use of outcomes-based tests for detecting racial bias in the context of police searches of motor vehicles. It shows that the test proposed in Knowles, Persico and Todd (2001) can also be applied in a more general environment where police officers are heterogenous in their tastes for discrimination and in their costs of search and motorists are heterogeneous in their benefits and costs from criminal behavior. We characterize the police and motorist decision problems in a game theoretic framework and establish properties of the equilibrium. We also extend of the model to the case where drivers’ characteristics are mutable in the sense that drivers can adapt some of their characteristics to reduce the probability of being monitored. After developing the theory that justifies the application of outcomes-based tests, we apply the tests to data on police searches of motor vehicles gathered by the Wichita Police department. The empirical findings are consistent with the notion that police in Wichita choose their search strategies to maximize successful searches, and not out of racial bias.Racial Profiling, Crime, Police, Wichita

Using Hit Rate Tests to Test for Racial Bias in Law Enforcement: Vehicle Searches in Wichita

This paper considers the use of outcomes-based tests for detecting racial bias in the context of police searches of motor vehicles. It shows that the test proposed in Knowles, Persico and Todd (2001) can also be applied in a more general environment where police officers are heterogenous in their tastes for discrimination and in their costs of search and motorists are heterogeneous in their benefits and costs from criminal behavior. We characterize the police and motorist decision problems in a game theoretic framework and establish properties of the equilibrium. We also extend the model to the case where drivers' characteristics are mutable in the sense that drivers can adapt some of their characteristics to reduce the probability of being monitored. After developing the theory that justifies the application of outcomes-based tests, we apply the tests to data on police searches of motor vehicles gathered by the Wichita Police deparment. The empirical findings are consistent with the notion that police in Wichita choose their search strategies to maximize successful searches, and not out of racial bias.

On a general extending and constraining procedure for linear iterative methods

Algebraic Reconstruction Techniques (ART), on their both successive or simultaneous formulation, have been developed since early 70's as efficient ''row action methods'' for solving the image reconstruction problem in Computerized Tomography. In this respect, two important development directions were concerned with, firstly their extension to the inconsistent case of the reconstruction problem, and secondly with their combination with constraining strategies, imposed by the particularities of the reconstructed image. In the first part of our paper we introduce extending and constraining procedures for a general iterative method of ART type and we propose a set of sufficient assumptions that ensure the convergence of the corresponding algorithms. As an application of this approach, we prove that Cimmino's simultaneous reflections method satisfies this set of assumptions, and we derive extended and constrained versions for it. Numerical experiments with all these versions are presented on a head phantom widely used in the image reconstruction literature. We also considered hard thresholding constraining used in sparse approximation problems and applied it successfully to a 3D particle image reconstruction problem

Racial Bias in Motor Vehicle Searches: Theory and Evidence

African- American motorist in the United States are much more likely than white motorists to have their car searched by police checking for illegal drugs and other contraband. The courts are faced with the task of deciding on the basis of traffic-search data whether police behavior reflects a rackial bias. We discuss why a simple test for racial bias commonly applied by the courts is inadequate and develop a model of law enforcement that suggests an alternative test. The model assumes a population with two racial types who also differ along other dimensions relevant to criminal behavior. Using the model, we construct a test for whether racial disparities in motor vehicle searches reflect racial prejudice, or instead are consistent with the behavior of non-prejudiced police maximizing drug interdiction. The test is valid even when the set of characteristics observed by the police is only partially observable by the econometrician. We apply the test to traffic-search data from Maryland and find the observed black-white disparities in search rates to be consistent with the hypothesis of no racial prejudice. Finally, we present a simple analysis of the tradeoff between efficiency of drug interdiction and racial fairness in policing. We show that in some circumstances there is no trade-off; constraining the police to be color-blind may achieve greater efficiency in drug interdiction.

User Requirements and Relational Modelling for a Non-Theatrical Cinema and Video-Art Cataloguing System

We describe an ongoing effort to design and implement a computerized cataloguing system for a laboratory dedicated to the resto- ration and archiving of non-theatrical cinema and video art. The goal is to evolve the current information system taking into account three different aspects: (i) national and international standards and workflows concerning preservation, cataloguing and archiving of film and contem- porary art; (ii) specific needs emerging by daily experimentation in film and video restoration practice; (iii) the interoperability with film archives and contemporary art museums. A flexible conceptual Relational model based on Codd\u2019s RM/T is proposed as a first step towards the development of a system meeting the unique requirements of non-feature films and videos

Pilotstudie zu vier Untertests des AID als Gruppenversion

Die vorliegende Arbeit ist als Weiterführung der Diplomarbeitsstudien von Böck (2010) und Eiter (2011) zu sehen, die es sich zum Ziel gesetzt haben für ausgewählte Subtests des AID 2 nach itemgenerierenden Regeln ein Itempool für eine Gruppen- beziehungsweise PC-Version des AID 2 zu entwickeln. Zu diesem Zweck wurden sowohl in den Vorgängerstudien, als auch in der aktuellen Studie, Kinder und Jugendliche zwischen 8;0 und 15;11 Jahren in vier oberösterreichischen Schulen mit dem neu entwickelten psychologisch-diagnostischen Verfahren getestet. In der vorliegenden Studie wurden die Daten von Böck (2010) und Eiter (2011) nach Verdopplung der Stichprobe auf etwa 1400 Testpersonen und unter Verwendung eines verlinkten Designs einer Reanalyse hinsichtlich der Konformität mit dem dichotomen logistischen Modell nach Rasch unterzogen. Die Modellgültigkeit wurde mit dem Likelihood-Ratio-Test nach Andersen (1973) hinsichtlich der Teilungskriterien Score, Alter und Geschlecht überprüft. Für den Subtest „Funktionen Abstrahieren“ konnte nach Ausschluss problematischer Items Rasch-Modell-Gültigkeit angenommen werden. Für die Untertests „Angewandtes Rechnen“ und „Wortschatz“ zeigten sich im LR-Test für das Teilungskriterium Alter signifikante Abweichungen vom Modell. Der letzte Untertest „Alltagswissen“ kann, wie bereits in der Vorgängerstudie, nicht als Rasch-Modell-konform bezeichnet werden. Hier ist eine Überprüfung und Überarbeitung der itemgenerierenden Regeln anzudenken. Generell legt für Folgeuntersuchungen die Überprüfung der itemgenerierenden Regeln an Hand des LLTM nahe.This diploma thesis represents a continuation of the studies by Böck (2010) and Eiter (2011), who developed new items for selected subtests of the AID 2 using a rule-based approach. Their goal was to develop an item pool for a group or PC version of the AID 2. Their target group consisted of children and adolescents between 8;0 and 15;11 years of age who were tested in four different schools in Upper Austria. While focusing on the same target group, this study doubled the sample to 1400 subjects and re-analyzed the data according to the Rasch-Model using a linked design. The validity of the Rasch-Model has been evaluated through the Likelihood-Ratio Test by Andersen (1973), using the split-criteria score, age and gender. For the subtest "abstracting functionalities" (“Funktionen Abstrahieren”), Rasch-Model validity could be assumed after excluding problematic items. For the subtests "applied mathematics" (Angewandtes Rechnen”) and "vocabulary" (“Wortschatz”), there were significant deviations from the model shown in the LR-test for the split-criterion “age”. The last test, "everyday knowledge" ("Alltagswissen"), can, as in the previous study, not be called Rasch-Model compliant. A review and revision of the rules for item development is necessary. For follow-up studies it is generally suggested to check the rules-generating guidelines using the LLTM (linear logistic test model)

„Wegsehen darf man nicht – aber auch nicht alles zeigen“. Bildethik aus Sicht des katholischen Hilfswerks Adveniat. Ein Gespräch mit Nicola van Bonn

Enthauptungsvideos der Terrorgruppe „Islamischer Staat“, Fotos verbrannter Leichen, schwerverletzte Menschen im Fokus der Kamera: Gräueltaten gibt es auf der Welt viele und entsprechend groß ist die Menge fotografischer Dokumentationen dieser Taten. Viele Redakteure suchen bei der Bildauswahl für ihr Medium tagtäglich die richtige Balance zwischen journalistischer Aufklärungspflicht und abstoßendem Schrecken. Eine von ihnen ist Nicola van Bonn von der Abteilung Öffentlichkeitsarbeit von „Adveniat“, dem bischöflichen Lateinamerika-Hilfswerk der katholischen Kirche in Deutschland. Sie ist verantwortliche Redakteurin des Printmagazins „Blickpunkt Lateinamerika“ und der dazugehörigen Internetseite www.blickpunkt-lateinamerika.de. Mit ihr sprach unsere Redakteurin Petra Hemmelmann

Calculus Early Transcendentals Integral & Multi-Variable Calculus for Social Sciences

Calculus Early Transcendentals Integral & Multi-Variable Calculus for Social Sciences has been redesigned in the Department of Mathematics at Simon Fraser University from Calculus Early Transcendentals by Lyryx. Substantial portions of the content, examples, and diagrams have been redeveloped to meet the needs of social science calculus. Additional contributions have been provided by an experienced and practicing instructor. The textbook is approachable, cohesive, and suitable for  standard integral calculus courses offering a comprehensive treatment of the necessary calculus techniques and concepts. Information about what was changed in this adaptation is found in the Copyright statement on page iii of the textbook

Calculus Early Transcendentals Differential & Multi-Variable Calculus for Social Sciences

Calculus Early Transcendentals Differential & Multi-Variable Calculus for Social Sciences has been redesigned in the Department of Mathematics at Simon Fraser University from Calculus Early Transcendentals by Lyryx. Substantial portions of the content, examples, and diagrams have been redeveloped to meet the needs of social science calculus. Additional contributions have been provided by an experienced and practicing instructor. The textbook is approachable, cohesive, and suitable for  standard differential calculus courses offering a comprehensive treatment of the necessary calculus techniques and concepts. Information about what was changed in this adaptation is found in the Copyright statement on page iii of the textbook

FPGA Implementation of Gaussian Mixture Model Algorithm for 47 fps Segmentation of 1080p Video

Circuits and systems able to process high quality video in real time are fundamental in nowadays imaging systems. The circuit proposed in the paper, aimed at the robust identification of the background in video streams, implements the improved formulation of the Gaussian Mixture Model (GMM) algorithm that is included in the OpenCV library. An innovative, hardware oriented, formulation of the GMM equations, the use of truncated binary multipliers, and ROM compression techniques allow reduced hardware complexity and increased processing capability. The proposed circuit has been designed having commercial FPGA devices as target and provides speed and logic resources occupation that overcome previously proposed implementations. The circuit, when implemented on Virtex6 or StratixIV, processes more than 45 frame per second in 1080p format and uses few percent of FPGA logic resources