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Examination of the performance of different pointwise linear regression progression criteria to detect glaucomatous visual field change

De Moraes, Carlos G.; Liebmann, Craig A.; Susanna, Remo, Jr.; Ritch, Robert; Liebmann, Jeffrey M.
Fonte: WILEY-BLACKWELL; HOBOKEN Publicador: WILEY-BLACKWELL; HOBOKEN
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
45.93%
Background: We aimed to investigate the performance of five different trend analysis criteria for the detection of glaucomatous progression and to determine the most frequently and rapidly progressing locations of the visual field. Design: Retrospective cohort. Participants or Samples: Treated glaucoma patients with =8 Swedish Interactive Thresholding Algorithm (SITA)-standard 24-2 visual field tests. Methods: Progression was determined using trend analysis. Five different criteria were used: (A) =1 significantly progressing point; (B) =2 significantly progressing points; (C) =2 progressing points located in the same hemifield; (D) at least two adjacent progressing points located in the same hemifield; (E) =2 progressing points in the same Garway-Heath map sector. Main Outcome Measures: Number of progressing eyes and false-positive results. Results: We included 587 patients. The number of eyes reaching a progression endpoint using each criterion was: A = 300 (51%); B = 212 (36%); C = 194 (33%); D = 170 (29%); and E = 186 (31%) (P = 0.03). The numbers of eyes with positive slopes were: A = 13 (4.3%); B = 3 (1.4%); C = 3 (1.5%); D = 2 (1.1%); and E = 3 (1.6%) (P = 0.06). The global slopes for progressing eyes were more negative in Groups B...

Estudo de tendências nas séries temporais de qualidade de água de rios do estado de São Paulo com diferentes graus de intervenção antrópica.; Trend analysis in water quality time series of rivers with different degrees of anthropogenic intervention in São Paulo State.

Groppo, Juliano Daniel
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 10/06/2005 PT
Relevância na Pesquisa
66%
O conhecimento das tendências temporais da qualidade das águas é importante no diagnóstico ambiental de bacias hidrográficas, permitindo avaliar como os corpos d’água vem respondendo ao longo dos anos, em termos qualitativos, à crescente intervenção antrópica. O objetivo deste trabalho é caracterizar a qualidade das águas dos rios das bacias do Piracicaba, Mogi-Guaçu, Turvo Grande, Peixe, Aguapeí, São José dos Dourados e Alto Paranapanema utilizando postos monitorados pela CETESB (Companhia de Tecnologia de Saneamento Ambiental), no período entre 1979 e 2001. Os parâmetros biogeoquímicos avaliados quanto a sua tendência temporal e magnitude foram: oxigênio dissolvido (OD), demanda bioquímica de oxigênio (DBO), nitrogênio total, nitrato, fósforo total, cloreto, amônio e coliformes fecais. A análise de tendência temporal exige uma metodologia específica, uma vez que as séries temporais obtidas não seguem uma distribuição normal, as amostragens são realizadas irregularmente, os dados apresentam sazonalidade e são dependentes da vazão dos rios. Essa metodologia é dividida em análise gráfica e aplicação de testes de tendência, onde inicialmente realiza-se uma análise exploratória dos dados, seguida da confirmação através de testes estatísticos. Os resultados mostraram que de uma maneira geral existe uma degradação da qualidade das águas na maior parte das bacias...

Deriva litorânea e evolução da linha de costa no sul do Espírito Santo (Brasil); Longshore drift and shoreline evolution in southern Espírito Santo (Brazil)

Contti Neto, Nery
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 19/04/2013 PT
Relevância na Pesquisa
45.93%
A deriva litorânea é estudada no litoral sul do Espírito Santo através de diferentes técnicas: distribuição de Minerais Pesados (MP); modelo conceitual Análise de Transport de Sedimento (Sediment Trend Analysis - STA), através da variação de parâmetros texturais do sedimento; dados de clima de onda entre 1997 e 2010 do modelo global WaveWatch III propagados para a zona costeira através do modelo Delft-3D, fornecendo parâmetros necessários para as equações de deriva; e imagens de satélite e fotografias aéreas para avaliar a variação espaço-temporal da morfologia costeira. O modelo STA mostrou-se confiável apenas nos dois setores ao norte, enquanto nos demais os resultados foram mascarados por altos teores de MP e/ou carbonato e a entrada de outras fácies no sistema; as equações representaram bem a variação da morfologia costeira na área de estudos. De maneira geral, os setores ao sul apresentaram transporte longitudinal para sul, e os setores ao norte, para norte, fato relacionado à batimetria local. A orientação da linha de costa auxiliou na compreensão dos fenômenos erosivos, pois em sua maioria estão orientados no sentido NEN, formando 45º com as ondas dos setores de ESE e SE.; Longshore drift is studied in the southern portion of Espírito Santo through different techniques: Heavy Minerals (HM) distribution; the conceptual model Sediment Trend Analysis (STA) by sediment textural parameters fluctuation; wave climate data between 1997 and 2010 from WaveWatch III propagated to the coastal zone through Delft-3D model...

Sediment Transport using Grain Size Trend Analysis: A Case Study in SW of Portugal

Du, XIAOQIN; Gama, Cristina; Liu, James
Fonte: Asia Oceania Geosciences Society- AOGS 2011 Publicador: Asia Oceania Geosciences Society- AOGS 2011
Tipo: Aula
ENG
Relevância na Pesquisa
66.04%
As a embayed coast, the main sediment sources are fluvial discharges, sea-cliff erosion and sand carried by longshore currents [1]. The particles are transported in suspended load or bedload pattern under the coactions of tidal currents and waves. In response to sediment transport processes, the spatial variations in the grain-size parameters exist, that reflect the net particles transport trend and the dynamic conditions. Thus, the grain size trend analysis was developed to study the net sediment transport. The study area is an embayed coast from Troia to Sines in SW of Portugal. There is a cape in the south end while the north end is a mountain belt with 35 km in length and 500 m in height [2]. A river with small discharge lies in the north. The tidal range varies between 1.5~3.5 m while the swell and winds from the west and northwest are dominant [3]. Therefore, the study area is sheltered from persist winds from north in summer and exposed to the storm waves from southwest in winter. The surfical sediment was sampled in the shallow water in 1980, 1983 and 1985, respectively. In order to obtain the important sediment source and sediment transport trend, three approaches were used: (1) the EOF (Empirical Orthogonal Function) analysis technique; (2) the McLaren Model; (3) grain size trend analysis. The wave is dominant in the study area. The result of EOF analysis shows that the most important sediment source is cliff erosion. The sediment eroded from cliffs during storms and high waves was transported off-shore and southward in the south part during high energy effect...

Análise global de tendências em contagens de fogos noturnos ativos (1996 - 2012)

Pinto, Diogo Miguel da Silva de Sousa
Fonte: Universidade Técnica de Lisboa Publicador: Universidade Técnica de Lisboa
Tipo: Dissertação de Mestrado
Publicado em //2014 POR
Relevância na Pesquisa
45.95%
Mestrado em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de Agronomia; This thesis aimed to perform a trend analysis of the global distribution of vegetation fires for the period from June 1996 to March 2012. We used the product from the World Fires Atlas (WFA) from the European Space Agency (ESA), obtained with the Along Track Scanning Radiometer (ATSR) sensor onboard the Second European Remote Sensing Satallite (ERS – 2), under which a filtering process was applied, following the same method of Mota et al. (2006). We conducted a comparative analysis between the initial data and the clean data and there was a percentage of false alarmes and fires that were not vegetation fires of 28%. The errors obtained were due primarily to hot surfaces and gas flares. With the data obtained, we conducted a trend analysis by performing the Mann-Kendall test in the program IDRISI Selva. The mapping created by the test, was studied to identity the presence of positive or negative trends. After a close visual study of the mapping and after the analysis of the temporal profiles of places of interest, we concluded that there is no relevant trend present globally, both positive or negative.

Cirrhosis mortality and per capita consumption of distilled spirits, United States, 1949-1994: trend analysis.

Roizen, R; Kerr, W C; Fillmore, K M
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/1999 EN
Relevância na Pesquisa
45.88%
OBJECTIVE: To describe, evaluate, and suggest interpretations for an observed aggregate-level relation between trends in mortality from cirrhosis and per capita consumption of distilled spirits in the United States. DESIGN: Trend analysis using data on US cirrhosis mortality and per capita alcohol consumption. RESULTS: There is a consistent long-term trend relation between mortality from cirrhosis and per capita consumption of distilled spirits in the United States from 1949 to 1994. Two instances of comparatively sharp drops in the consumption of spirits in the 1940s generated mixed results in predicting changes in cirrhosis mortality. CONCLUSIONS: An aggregate-level relation between trends in long-term cirrhosis mortality and the consumption of spirits falls considerably short of establishing a direct causal link between the two for individuals. Moreover, two sharp drops in the consumption of spirits generated only mixed results with respect to the short-term trend in cirrhosis. Nevertheless, the observed relation between the consumption of spirits and cirrhosis mortality merits further investigation.

Time trend analysis of gastric cancer incidence in Japan by histological types, 1975-1989

Kaneko, S; Yoshimura, T
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em /02/2001 EN
Relevância na Pesquisa
45.92%
Since different histological types (HT) of gastric cancer (GC) may differ in their aetiology, time trend analysis by HT may afford an insight into aetiology. From the Gastric Cancer Registry of Japan, 161 067 cases diagnosed were retrieved between 1975 and 1989 to calculate the annual relative frequencies, stratified by age group and sex, of HT according to the Lauren and the Japanese Research Society for Gastric Cancer (JRSGC) classifications. Age- and sex-specific incidence rates by HT were estimated by multiplying the corresponding national cancer incidence rates of GC by the relative frequencies. Logistic regression models stratified by sex and age group were fitted to determine the time trends of HT. Using the Lauren classification, a decreasing trend of the intestinal type and a stable trend of the diffuse type were found. By the JRSGC classification, significant decreasing trends for most age groups were found for papillary and mucinous adenocarcinomas. Tubular adenocarcinomas (well differentiated type) showed a decreasing trend only in younger age groups. Tubular (moderately differentiated type), poorly differentiated adenocarcinomas, and signet ring cell carcinoma were statistically stable during the period. Considering changes in lifestyles of the Japanese...

Trends in hydrologic time series and the climate change: some of the portuguese experience

Santos, João Filipe; Portela, Maria Manuela; Quintela, António de Carvalho; Vaz, Cristiana
Fonte: Repositório Comum de Portugal Publicador: Repositório Comum de Portugal
Tipo: Conferência ou Objeto de Conferência
Publicado em //2009 ENG
Relevância na Pesquisa
45.95%
Comunicação apresentada no EcoHCC'09 - International Conference on Ecohydrology and Climate Change, Tomar (Portugal); Nowadays it is often mentioned that the Earth is already suffering the climate change effects: it is no longer a matter of future climate scenarios but instead of frequent abnormal climate occurrences. If changes are already happening then they should be embedded in some of the hydrologic time series, with emphasis to those series more closely related to the weather, as the precipitation series. In the previous scope a research is been carried since the last years aiming at detecting trends in Portuguese hydrologic time series by means of statistical and simulation approaches and at relating such trends with the climate change. The results from the trend analysis applied to precipitation series in more than one hundred rain gages showed that some months exhibit a upwards trend while other months denote a downward trend or even no trend at all. Changes in the precipitation monthly pattern may also seam to occur, those changes compensating each others and resulting in unchanged annual precipitations. In general terms, the study showed that, except for March, most of the trends are not significant from a statistical point of view...

análisis tendencial de la variación climática “temperatura y precipitación” espacio-temporal del departamento de boyacá (colombia); TREND ANALYSIS OF CLIMATE CHANGE “TEMPERATURE AND PRECIPITATION "SPACE-TIME DEPARTMENT BOYACA (COLOMBIA)

Socha Roncón, Liliana Marcela; Corredor, Jorge
Fonte: Universidad Militar Nueva Granada; Facultad de Ingeniería; Especialización en Geomática Publicador: Universidad Militar Nueva Granada; Facultad de Ingeniería; Especialización en Geomática
Tipo: bachelorThesis; Trabajo de grado Formato: pdf; pdf
SPA
Relevância na Pesquisa
55.79%
Con el fin de estudiar uno de los factores más importantes en la afectación humana se ha llevado a cabo un análisis de las series de tiempo de 29 estaciones meteorológicas del Departamento de Boyacá, con registros que datan de 1997 y 2001 con el cual se pretende analizar la variabilidad espacial en la distribución geográfica sobre el territorio boyacense de la temperatura, así como el cambio en la precipitación llevado a cabo mediante el promedio medio mensual anual de la temperatura y la precipitación calculado entre los 2 años de registros mensuales; To study one of the most important factors in human involvement has been carried out an analysis of the time series of 29 meteorological seasons of Department of Boyacá, with records dating back to 1997 and 2001 with which to analyze spatial variability in the geographical distribution of the territory boyacense temperature and change in precipitation carried out by the average monthly temperature and precipitation de Calculated in 2 years of monthly records

An Interactive Patient Data Base for Intensive Care Trend Analysis

Gomez, J. V.; Haddad, A. G.; Mentz, W. M.; Friedman, M.; Charlton, J. D.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 26/10/1983 EN
Relevância na Pesquisa
45.87%
An interactive patient data base system for recording of patient data and trend analysis was developed for use in a respiratory intensive care unit. The system incorporates patient demographic information, as well as forty-five numerical cardiopulmonary variables. Numerical data may be displayed in either tabular or graphical form. Graphical trend analysis is allowed in time or between any selected variables. In addition, the system allows for removal of patient data (at the end of the patient's stay) for compact, permanent storage on a floppy disk.

OPIUM ADDICTION IN ASSAM : A TREND ANALYSIS

Mahantra, J.; Chaturvedi, H.K.; Phukan, R.K.
Fonte: Medknow Publications Publicador: Medknow Publications
Tipo: Artigo de Revista Científica
Publicado em //1997 EN
Relevância na Pesquisa
45.88%
A survey on opium use was earned out in Tinsukia district of upper Assam to assess the present prevalence and pattern of opium abuse and compared with earlier findings of the year 1981 (Baruah et al., 1995). A total of 75 addicts could be detected during the survey and 61 were interviewed using structured questionnaire. The results indicate significant decline in prevalence in opium use over the years in all the villages under high prevalence area. Out of 61 addicts, 51 addicts had started taking opium before 1980 and only 10 new addicts were added by 1990. The trend analysis of opium user's from 1979 to 1995 indicates a linear trend with high rate of decline in opium addicts statistical analyses, supports the hypothesis that linear declining trend is the best fit. By 1995, only four addicts were found having continued taking of opium.

Trend in mortality due to external causes in the State of Espírito Santo, Brazil, from 1994 to 2005

Jacobson,Ludmilla da Silva Viana; Andrade,Carla Lourenço Tavares de; Carmo,Cleber Nascimento do; Mourão,Dennys de Souza; Hacon,Sandra de Souza
Fonte: Associação Brasileira de Saúde Coletiva Publicador: Associação Brasileira de Saúde Coletiva
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2009 EN
Relevância na Pesquisa
45.91%
The aim of this study was to analyze the trend in mortality due to external causes in the State of Espírito Santo, Brazil, from 1994 to 2005, according to specific groups (traffic injuries, poisoning, intentional self-harm, assault), age group and gender. The trend analysis was performed with polynomial regression models, based on data from the Brazilian Ministry of Health's Mortality Information System. For all external causes, the trend was not statistically significant, but when it was stratified by gender and age group the results showed a downward trend in some strata. According to gender, the yearly increase in mortality rate was higher for men. In general, this increase was observed in all age groups. For traffic injuries, there was a decrease in the mortality rate, mainly for men. There was a decrease in deaths from poisoning for both men and women. Intentional self-harm showed an upward trend, especially for 50 and over age group. As a specific group, assault also showed a significant upward trend for under-34 age groups and for men.

Stock Market Trend Analysis Using Hidden Markov Models

Kavitha, G.; Udhayakumar, A.; Nagarajan, D.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 19/11/2013
Relevância na Pesquisa
45.88%
Price movements of stock market are not totally random. In fact, what drives the financial market and what pattern financial time series follows have long been the interest that attracts economists, mathematicians and most recently computer scientists [17]. This paper gives an idea about the trend analysis of stock market behaviour using Hidden Markov Model (HMM). The trend once followed over a particular period will sure repeat in future. The one day difference in close value of stocks for a certain period is found and its corresponding steady state probability distribution values are determined. The pattern of the stock market behaviour is then decided based on these probability values for a particular time. The goal is to figure out the hidden state sequence given the observation sequence so that the trend can be analyzed using the steady state probability distribution( ) values. Six optimal hidden state sequences are generated and compared. The one day difference in close value when considered is found to give the best optimum state sequence.; Comment: International Journal of Computer Science and Information Security october 2013

Multiscale Trend Analysis

Zaliapin, I.; Gabrielov, A.; Keilis-Borok, V.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
55.81%
This paper introduces a multiscale analysis based on optimal piecewise linear approximations of time series. An optimality criterion is formulated and on its base a computationally effective algorithm is constructed for decomposition of a time series into a hierarchy of trends (local linear approximations) at different scales. The top of the hierarchy is the global linear approximation over the whole observational interval, the bottom is the original time series. Each internal level of the hierarchy corresponds to a piecewise linear approximation of analyzed series. Possible applications of the introduced Multiscale Trend Analysis (MTA) go far beyond the linear interpolation problem: This paper develops and illustrates methods of self-affine, hierarchical, and correlation analyses of time series.; Comment: 37 pages, 19 figures

Principal trend analysis for time-course data with applications in genomic medicine

Zhang, Yuping; Davis, Ronald
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 13/01/2014
Relevância na Pesquisa
45.87%
Time-course high-throughput gene expression data are emerging in genomic and translational medicine. Extracting interesting time-course patterns from a patient cohort can provide biological insights for further clinical research and patient treatment. We propose principal trend analysis (PTA) to extract principal trends of time-course gene expression data from a group of patients, and identify genes that make dominant contributions to the principal trends. Through simulations, we demonstrate the utility of PTA for dimension reduction, time-course signal recovery and feature selection with high-dimensional data. Moreover, PTA derives new insights in real biological and clinical research. We demonstrate the usefulness of PTA by applying it to longitudinal gene expression data of a circadian regulation system and burn patients. These applications show that PTA can extract interesting time-course trends with biological significance, which helps the understanding of biological mechanisms of circadian regulation systems as well as the recovery of burn patients. Overall, the proposed PTA approach will benefit the genomic medicine research. Our method is implemented into an R-package: PTA (Principal Trend Analysis).; Comment: Published in at http://dx.doi.org/10.1214/13-AOAS659 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org)

Methods for the analysis of trends in streamflow response due to changes in catchment condition

Letcher, Rebecca; Schreider, Sergei; Jakeman, Anthony; Neal, B; Nathan, Rory John
Fonte: John Wiley & Sons Inc Publicador: John Wiley & Sons Inc
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
55.87%
Two algorithms for analysing changes in streamflow response due to changes in land use and farm dam development, based on the Estimated Generalized Least Squares (EGLS) and the Generalized Additive Model (GAM) methods, were compared on three catchments in the Macquarie River Basin in NSW, Australia. In order to account for the influence of climatic conditions on streamflow response, the IHACRES conceptual rainfall-runoff model was calibrated on a daily time step over two-year periods then simulated over the entire period of concurrent rainfall, streamflow and temperature data. Residuals or differences between observed and simulated flows were calculated. The EGLS method was applied to a smoothing of the residual (daily) time series. Such residuals represent the difference between the simulated streamflow response to a fixed catchment condition (in the calibration period) and that due to the actual varying conditions throughout the record period. The GAM method was applied to quarterly aggregated residuals. The methods provided similar qualitative results for trends in residual streamflow response in each catchment for models with a good fitting performance on the calibration period in terms of a number of statistics, i.e. the coefficient of efficiency R2...

Análise de tendências da produção científica nacional na área de Ciência da Informação: estudo exploratório de mineração de textos; El análisis de tendencias de la producción científica brasileña en el área de Ciencia de la Información: una investigación exploratoria de minería de texto; Trend analysis of the Brazilian scientific production in Information Science area: a text mining exploratory study

Trucolo, Caio Cesar; Universidade de São Paulo - USP; Digiampietri, Luciano Antonio; Universidade de São Paulo - USP
Fonte: Mestrado Interdisciplinar em Ciência, Gestão e Tecnologia da Informação - UFPR Publicador: Mestrado Interdisciplinar em Ciência, Gestão e Tecnologia da Informação - UFPR
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Artículo evaluado por pares; estudio cuantitativo; ; quantitative study; Avaliado pelos pares; Estudo quantitativo Formato: text/html; application/pdf; application/epub+zip
Publicado em 05/03/2015 POR
Relevância na Pesquisa
66.03%
Introdução: A análise de tendências pode ser utilizada como uma estratégia para identificar assuntos ou áreas de pesquisa com potencial de popularidade, mas que ainda não são disseminados amplamente. Este trabalho consiste em identificar tendências por mineração de texto e análise histórica das produções científicas (artigos científicos) de doutores da área de Ciência da Informação. Método: De natureza exploratória, este trabalho foi construído em três etapas. A primeira etapa foi a obtenção dos dados dos currículos cadastrados na plataforma Lattes. A segunda etapa consistiu na extração automática dos termos mais importantes inseridos nos títulos das publicações e, na terceira etapa foram feitas regressões lineares e não lineares dos índices de importância baseados em frequência dos termos extraídos. Resultados: Informações gerais sobre as tendências identificadas para a área de Ciência de Informação para curto, médio e longo prazo são apresentadas. Conclusão: Apresenta e aplica uma metodologia de identificação de tendências que ainda pode ser considerada um primeiro passo ante ao potencial da análise de tendências para a produção científica nacional. Além disso, informações gerais sobre as tendências identificadas e os comportamentos dessas tendências ao longo do tempo foram discutidas.; Introduction: Trend analysis can be used as a strategy to identify subjects or research areas with potential of popularity which are not very widespread. This work consists of trend identification by text mining and historic analysis of the scientific productions (scientific papers) of the Information Science area PhD s. Method: This work...

Analysis of the maximum daily temperature evolution on the Spanish Central Plateau

Labajo,J. L.; Labajo,A. L.; Egido,M.; Martín,Q.; Morales,C.; Ortega,M. T.
Fonte: Centro de Ciencias de la Atmósfera, UNAM Publicador: Centro de Ciencias de la Atmósfera, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2012 EN
Relevância na Pesquisa
45.93%
An analysis of the temporal behavior of the annual and seasonal frequencies of extreme maximum daily temperature values on the Spanish Central Plateau is performed. With the daily data on maximum temperatures measured at 14 weather stations, between 1961 and 2003, we constructed a series of maximum daily temperature anomalies for each of the observatories and in the study zone, and also in the two subzones into which the Central Plateau can be divided. To determine the highest and lowest extreme values of the maximum daily temperature anomalies, the P05 and P95 percentiles of the anomaly series were considered as thresholds. Next we constructed the series of annual frequencies of days with the highest and lowest extreme values of maximum daily temperature anomalies. Trend analysis of these series revealed that during the period studied the annual frequency of the lowest extreme cases of maximum daily temperature anomalies has tended to decrease while that of the highest ones has tended to increase. From an analysis of the temporal evolution of the annual frequencies it may be deduced that a variation in the trend occurred around 1972, variation previously established for other variables (pressure, annual mean temperature, etc.) in the area of study. The results obtained upon considering the interval of time between 1973 and 2003 indicate that the trend was the same as that obtained for the whole period studied but the level of confidence is higher. Finally...

A theory of quantitative trend analysis and its application to South African general elections

Greben,Jan M.
Fonte: South African Journal of Science Publicador: South African Journal of Science
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2007 EN
Relevância na Pesquisa
45.93%
Trends are usually defined as progressive changes in a particular phenomenon. If the phenomenon can be characterized by one variable over time (such as the price of some item), then a trend analysis is fairly simple. Phenomena are often characterized, however, by more than one variable at particular discrete time intervals. In such cases a trend analysis becomes more complex and ambiguous. If enough data are available, however, trends between two subsequent times can be represented by so-called transition matrices. The theory of such matrices for the description of voting patterns was developed in the United Kingdom in the 1970s. South African general elections represent an ideal test case for such theories as both the number of independent results (17 000 voting districts versus about 240 three-way contested constituencies in the U.K.) and the number of parties (about 20 versus 4 in Britain) are much greater in the South African case. This paper reports such a trend analysis using extensions of previous methods, and introduces two new methods to avoid negative transition matrix elements. The applicability of the old and new methods is discussed and their results examined. Other areas of application of transition matrices to trends are briefly reviewed.

Trend in mortality due to external causes in the State of Espírito Santo, Brazil, from 1994 to 2005

Jacobson,Ludmilla da Silva Viana; Andrade,Carla Lourenço Tavares de; Carmo,Cleber Nascimento do; Mourão,Dennys de Souza; Hacon,Sandra de Souza
Fonte: Associação Brasileira de Pós -Graduação em Saúde Coletiva Publicador: Associação Brasileira de Pós -Graduação em Saúde Coletiva
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2009 EN
Relevância na Pesquisa
45.91%
The aim of this study was to analyze the trend in mortality due to external causes in the State of Espírito Santo, Brazil, from 1994 to 2005, according to specific groups (traffic injuries, poisoning, intentional self-harm, assault), age group and gender. The trend analysis was performed with polynomial regression models, based on data from the Brazilian Ministry of Health's Mortality Information System. For all external causes, the trend was not statistically significant, but when it was stratified by gender and age group the results showed a downward trend in some strata. According to gender, the yearly increase in mortality rate was higher for men. In general, this increase was observed in all age groups. For traffic injuries, there was a decrease in the mortality rate, mainly for men. There was a decrease in deaths from poisoning for both men and women. Intentional self-harm showed an upward trend, especially for 50 and over age group. As a specific group, assault also showed a significant upward trend for under-34 age groups and for men.