scholarly journals Anchored k-medoids: a novel adaptation of k-medoids further refined to measure long-term instability in the exposure to crime

Author(s):  
Monsuru Adepeju ◽  
Samuel Langton ◽  
Jon Bannister

AbstractLongitudinal clustering techniques are widely deployed in computational social science to delineate groupings of subjects characterized by meaningful developmental trends. In criminology, such methods have been utilized to examine the extent to which micro places (such as streets) experience macro-level police-recorded crime trends in unison. This has largely been driven by a theoretical interest in the longitudinal stability of crime concentrations, a topic that has become particularly pertinent amidst a widespread decline in recorded crime. Recent studies have tended to rely on a generic implementation k-means to unpick this stability, with little consideration for its theoretical suitability. This study makes two methodological contributions. First, it demonstrates the application of k-medoids to study longitudinal crime concentrations, and second, it develops a novel ‘anchored k-medoids’ (ak-medoids), a bespoke clustering method specifically designed to meet the theoretical requirements of micro-place investigations into long-term stability. Using both simulated data and 15-years of police-recorded crime data from Birmingham, England, we compare the performances of k-medoids against ak-medoids. We find that both methods highlight instability in the exposure to crime over time, but the consistency and contribution of cluster solutions determined by ak-medoids provide insight overlooked by k-medoids, which is sensitive to short-term fluctuations and subject starting points. This has important implications for the theories said to explain longitudinal crime concentrations, and the law enforcement agencies seeking to offer an effective and equitable service to the public.

Author(s):  
Stacy Wood

This paper considers the history and politics of ‘police data.’ Police data, I contend, is a category of endangered data reliant on voluntary and inconsistent reporting by law enforcement agencies; it is also inconsistently described and routinely housed in systems that were not designed with long-term strategies for data preservation, curation or management in mind. Moreover, whereas US law enforcement agencies have, for over a century, produced and published a great deal of data about crime, data about the ways in which police officers spend their time and make decisions about resources—as well as information about patterns of individual officer behavior, use of force, and in-custody deaths—is difficult to find. This presents a paradoxical situation wherein vast stores of extant data are completely inaccessible to the public. This paradoxical state is not new, but the continuation of a long history co-constituted by technologies, epistemologies and context.


2017 ◽  
Vol 9 (1) ◽  
pp. 168
Author(s):  
Md Mostafizur Rahman ◽  
Mahmud Uz Zaman

Pharmaceuticals agglomerations consistently use their brand image and versatile product portfolios to consolidate their position in the financial sector, which is evident in their continuous profit making and expansion in market share. This paper explores the short-term and long-term investment attractiveness through ‘consumer centric decision’ approach in two selected pharmaceutical companies, Renata Limited and Orion Pharma Limited, of Bangladesh over the last three years’ period. This research adopts a systematic approach which primarily addresses the various concerns of investors to illustrate the decision-making process of the existing and future investors. Using primarily domestic transaction data, this study explores how the leading pharmaceuticals companies of Bangladesh effectively use the wide array of drug portfolios mix with appropriate branding techniques to increase their financial profit and market share simultaneously. Both SWOT analysis and Porters Five Forces Model explore the business analysis of Renata Limited in compare to Orion Pharma Limited that provides a conclusion regarding investors’ decision to invest in Renata Limited. Considering the financial analysis, Renata’s financial liquidity is not very satisfactory and could have been improved further if management is prudent on financial strategy settings. Findings of the business analysis indicate that Renata Limited would be a good investment choice for existing and prospective shareholders based on its opportunities for long term and short term growth and further expansion in developing the market. The results suggest that even lower liquidity coupled with higher interest borrowings can be balanced by posing positive picture to the public shareholders by returning the positive dividend to them.


2020 ◽  
pp. 95-99
Author(s):  
R. G. Kalustov

The article discusses the emergence and development, as well as existing approaches to understanding the concept of “public order”. The history of the formation of this category is examined by analyzing regulatory legal acts. This method allows you to track the change in value and determine how to correctly understand the “public order” today. Revealing the concept, ambiguity arises in understanding this category, in connection with which the most applicable approach is currently determined for use in practice by law enforcement agencies.


2020 ◽  
pp. 1-12
Author(s):  
Ayla Gülcü ◽  
Sedrettin Çalişkan

Collateral mechanism in the Electricity Market ensures the payments are executed on a timely manner; thus maintains the continuous cash flow. In order to value collaterals, Takasbank, the authorized central settlement bank, creates segments of the market participants by considering their short-term and long-term debt/credit information arising from all market activities. In this study, the data regarding participants’ daily and monthly debt payment and penalty behaviors is analyzed with the aim of discovering high-risk participants that fail to clear their debts on-time frequently. Different clustering techniques along with different distance metrics are considered to obtain the best clustering. Moreover, data preprocessing techniques along with Recency, Frequency, Monetary Value (RFM) scoring have been used to determine the best representation of the data. The results show that Agglomerative Clustering with cosine distance achieves the best separated clustering when the non-normalized dataset is used; this is also acknowledged by a domain expert.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hiroshi Okamura ◽  
Yutaka Osada ◽  
Shota Nishijima ◽  
Shinto Eguchi

AbstractNonlinear phenomena are universal in ecology. However, their inference and prediction are generally difficult because of autocorrelation and outliers. A traditional least squares method for parameter estimation is capable of improving short-term prediction by estimating autocorrelation, whereas it has weakness to outliers and consequently worse long-term prediction. In contrast, a traditional robust regression approach, such as the least absolute deviations method, alleviates the influence of outliers and has potentially better long-term prediction, whereas it makes accurately estimating autocorrelation difficult and possibly leads to worse short-term prediction. We propose a new robust regression approach that estimates autocorrelation accurately and reduces the influence of outliers. We then compare the new method with the conventional least squares and least absolute deviations methods by using simulated data and real ecological data. Simulations and analysis of real data demonstrate that the new method generally has better long-term and short-term prediction ability for nonlinear estimation problems using spawner–recruitment data. The new method provides nearly unbiased autocorrelation even for highly contaminated simulated data with extreme outliers, whereas other methods fail to estimate autocorrelation accurately.


Mathematics ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 620
Author(s):  
Ioannis Kyriakou ◽  
Parastoo Mousavi ◽  
Jens Perch Nielsen ◽  
Michael Scholz

The fundamental interest of investors in econometric modeling for excess stock returns usually focuses either on short- or long-term predictions to individually reduce the investment risk. In this paper, we present a new and simple model that contemporaneously accounts for short- and long-term predictions. By combining the different horizons, we exploit the lower long-term variance to further reduce the short-term variance, which is susceptible to speculative exuberance. As a consequence, the long-term pension-saver avoids an over-conservative portfolio with implied potential upside reductions given their optimal risk appetite. Different combinations of short and long horizons as well as definitions of excess returns, for example, concerning the traditional short-term interest rate but also the inflation, are easily accommodated in our model.


2003 ◽  
Vol 31 (S4) ◽  
pp. 81-83 ◽  
Author(s):  
Mary Anne Viverette ◽  
Jennifer Leaning ◽  
Susan K. Steeg ◽  
Kristine M. Gebbie ◽  
Maureen Litchveld

The Commission on the Accreditation of Law Enforcement (CALEA) employs rigorous evaluation techniques. Objective accreditation, such as made possible by CALEA, is important from the public’s perspective and in the national community of law enforcement.To counteract a general distrust of law enforcement agencies, the Law Enforcement Assistance Administration (LEAA) developed a grant to develop standards by which the quality and performance of law enforcement could be measured. LEAA developed 107 standards and, though well received by the law enforcement community, no single group or agency took the initiative to begin a program to evaluate and implement the standards. In 1979, the Department of Justice established an additional grant that effectively organized the four major law enforcement groups: the International Association of Chiefs of Police, the National Sheriff’s Association, the National Organization of Black Law Enforcement Executives, and the Police Executive Research Forum.


2014 ◽  
Vol 29 (4) ◽  
pp. 321-325
Author(s):  
Jovica Praskalo ◽  
Jasna Davidovic ◽  
Biljana Kocic ◽  
Monika Zivkovic ◽  
Svetlana Pejovic

In order to set up a successful mammography screening program in the Republic of Srpska, a Siemens Mammomat 1000 X-ray machine was selected for analysis as the said mammography system is widely used in clinical practice. The variations in tube parameters (specific air kerma, high-voltage accuracy and reproducibility, linearity between exposure and dose exposure time) were monitored over a five-year period, from 2008 to 2012. In addition, due to observed daily fluctuations for chosen parameters, a series of measurements were performed three times a day within a single-month period (mainly October 2012). The goal of such an experimental set up is to assess short-term and long-term stability of tube parameters in the given mammography unit and to make a comparison between them. The present paper shows how an early detection of significant parameter fluctuations can help eliminate irregularities and optimize the performance of mammography systems.


2018 ◽  
Vol 17 (2) ◽  
pp. 783-810
Author(s):  
Angélica Pott de Medeiros ◽  
Giulia Xisto de Oliveira ◽  
Reisoli Bender Filho

Resumo: O cenário de instabilidade política, a recessão econômica e as mudanças nas regras de concessão de crédito pautaram o objetivo de examinar o relacionamento do crédito consignado, por segmento de concessão, com variáveis macroeconômicas, caso do consumo, da produção industrial e do produto agregado, na última década (2007-2017). Os resultados foram obtidos por meio da estimação do vetor de correção de erros, funções de impulso-resposta e decomposição da variância, possibilitando a análise das relações de curto e de longo prazo entre as séries temporais e indicaram que as diferentes modalidades do crédito consignado implicam efeitos distintos sobre as variáveis econômicas em curto prazo. O segmento de aposentados e pensionistas impacta positivamente ambas as variáveis analisadas, com destaque para os bens de consumo das famílias. Já a concessão ao setor privado, embora represente a menor parcela do crédito consignado concedido, mostrou elevada sensibilidade a alterações na oferta dessa modalidade de crédito, enquanto que o crédito ao setor público, de maior participação, apresentou efeitos reduzidos e de curta duração.Palavras-chave: Crédito consignado. Segmentos. Economia brasileira. Payroll loans: segments and economic effects Abstract: The environment of political instability, economic recession and changes in the rules of granting credit were guiders to aim to examine the payroll loans relationship, by concession segment, with macroeconomic variables, case of consumption, industrial production and aggregate product, in the last decade (2007-2017). The results obtained by error correction vector estimation, and functions of impulse-response and variance decomposition, making it possible to analyze the short- and long-term relationships between the time series and indicated that the different modalities of payroll loans imply different effects on economic short-term variables. With retirees and pensioners segment positively impact on both analyzed variables, highlighting the household consumption goods. The concession to the private sector, although it represents the smallest portion of payroll loans granted, it showed high sensitivity to the changes of this modality. About credit to the public sector, which has the biggest portion, it showed reduced and short-term effects.Keywords: Payroll loans. Segments. Brazilian economy.


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