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| Registros recuperados: 76 | |
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| Celec,Peter. |
| Cyclic variations of variables are ubiquitous in biomedical science. A number of methods for detecting rhythms have been developed, but they are often difficult to interpret. A simple procedure for detecting cyclic variations in biological time series and quantification of their probability is presented here. Analysis of rhythmic variance (ANORVA) is based on the premise that the variance in groups of data from rhythmic variables is low when a time distance of one period exists between the data entries. A detailed stepwise calculation is presented including data entry and preparation, variance calculating, and difference testing. An example for the application of the procedure is provided, and a real dataset of the number of papers published per day in... |
| Tipo: Journal article |
Palavras-chave: Chronobiology; Time series; Method; ANORVA; Analysis of rhythmic variance; Circaseptan; Cycle; Rhyth. |
| Ano: 2004 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602004000500007 |
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| Martins,Tailon; Barreto,Alisson Castro; Coronel,Daniel Arruda; Jacobi,Luciane Flores; Lirio,Valentina Wolff; Souza,Adriano Mendonça. |
| ABSTRACT: The objective of this research was to forecast the Brazilian national production of agricultural and road machinery in the short term by BOX & JENKINS methodology and determine the persistence effect. Data were obtained at National Association of Automotive Vehicle Manufacturers (ANFAVEA) from January 1960 to October 2019, totaling 718 monthly observations. The Autoregressive Integrated Moving Average (ARIMA) and Autoregressive Conditional Heteroscedasticity (ARCH) methodology were used. The ARIMA (2,1,1)-ARCH (2) model was fitted and persistence of 0.60 was determined, showing that the instability in the series will be for a long period of time. |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Time series; Prediction; Volatility; Agricultural machinery; Road machinery. |
| Ano: 2020 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-84782020000600351 |
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| García Juárez, José de Jesús. |
| El objetivo de este trabajo es evaluar la eficiencia de las coberturas de precios de maíz blanco operadas por ASERCA. Para el estudio, se utiliza el análisis de cointegración de S. Johansen que consiste en probar la existencia de cointegración entre las variables de series de tiempo, en este caso: precios al mayoreo de maíz blanco, precio a futuro de maíz amarillo cotizado en la Bolsa de Futuros de Chicago (CBOT) y tipo de cambio peso-dólar; esta variable en particular, porque al adquirir una cobertura, existe también un riesgo cambiario dado que tanto la adquisición como la liquidación de las coberturas son realizadas en dólares. Los resultados indican que los precios de maíz al mayoreo de las centrales de abasto de Sinaloa, Jalisco, Estado de México,... |
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Palavras-chave: ASERCA; Cointegración; Riesgo; Serie de tiempo; Cointegration; Risk; Time series; Maestría; Economía. |
| Ano: 2011 |
URL: http://hdl.handle.net/10521/421 |
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| Islas Monroy, Juan Carlos. |
| Este trabajo muestra empíricamente la existencia del fenómeno de correlación espuria en modelos de regresión de respuesta binaria cuando los datos son generados por diferentes procesos de serie de tiempo. Los modelos estudiados son; el logístico, para observaciones independientes; un modelo de cadena de Markov de primer orden que considera dependencia entre las observaciones; y el de ecuaciones de estimación generalizadas para mediciones repetidas en estudios longitudinales. Los resultados indican que este fenómeno ocurre en los tres modelos de regresión excepto bajo algunas condiciones. Dada la hipótesis nula Ho:β1=0; en el modelo logístico y en el de cadena de Markov, el tamaño de la prueba presenta valores mucho mayores de lo esperado y aumenta... |
| Tipo: Tesis |
Palavras-chave: Modelos de respuesta binaria; Series de tiempo; Maestría; Estadística; Binary response models; Time series. |
| Ano: 2007 |
URL: http://hdl.handle.net/10521/1345 |
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| Islas Monroy, Juan Carlos. |
| Este trabajo muestra empíricamente la existencia del fenómeno de correlación espuria en modelos de regresión de respuesta binaria cuando los datos son generados por diferentes procesos de serie de tiempo. Los modelos estudiados son; el logístico, para observaciones independientes; un modelo de cadena de Markov de primer orden que considera dependencia entre las observaciones; y el de ecuaciones de estimación generalizadas para mediciones repetidas en estudios longitudinales. Los resultados indican que este fenómeno ocurre en los tres modelos de regresión excepto bajo algunas condiciones. Dada la hipótesis nula Ho:β1=0; en el modelo logístico y en el de cadena de Markov, el tamaño de la prueba presenta valores mucho mayores de lo esperado y aumenta... |
| Tipo: Tesis |
Palavras-chave: Modelos de respuesta binaria; Series de tiempo Binary response models; Time series. |
| Ano: 2012 |
URL: http://hdl.handle.net/10521/1017 |
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| García Juárez, José de Jesús. |
| El objetivo de este trabajo es evaluar la eficiencia de las coberturas de precios de maíz blanco operadas por ASERCA. Para el estudio, se utiliza el análisis de cointegración de S. Johansen que consiste en probar la existencia de cointegración entre las variables de series de tiempo, en este caso: precios al mayoreo de maíz blanco, precio a futuro de maíz amarillo cotizado en la Bolsa de Futuros de Chicago (CBOT) y tipo de cambio peso-dólar; esta variable en particular, porque al adquirir una cobertura, existe también un riesgo cambiario dado que tanto la adquisición como la liquidación de las coberturas son realizadas en dólares. Los resultados indican que los precios de maíz al mayoreo de las centrales de abasto de Sinaloa, Jalisco, Estado de México,... |
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Palavras-chave: ASERCA; Cointegración; Riesgo; Serie de tiempo; Cointegration; Risk; Time series; Maestría; Economía. |
| Ano: 2011 |
URL: http://hdl.handle.net/10521/421 |
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| Koedam, Nico; Vrije Universiteit Brussel; nikoedam@vub.ac.be; Ruiz Luna, Arturo; CIAD-Mazatlan; arluna@victoria.ciad.mx; Troell, Max; Beijer Institute; max@beijer.kva.se; Dahdouh-Guebas, Farid; Vrije Universiteit Brussel; fdahdouh@vub.ac.be. |
| The present study focuses on the Navachiste-San Ignacio-Macapule lagoon complex in northwest Mexico and evaluates the spatiotemporal change in the mangrove area over the last three decades using Landsat MSS and TM imagery. Local ethnobotanical uses of the mangrove forest and local perceptions about the status and recent development of the mangrove forest cover are also analyzed. The results of interviews with 54 inhabitants of four fishing villages in the study area indicated that, overall, Laguncularia racemosa is the most frequently used species in this region of the Mexican Pacific coast, where it serves as firewood and a construction material, particularly for walls and fences. The next-ranked species were Avicennia germinans, which is used for tea,... |
| Tipo: Peer-Reviewed Reports |
Palavras-chave: Mangrove; Ethnobiology; Remote sensing; Time series; Thematic Mapper; Multi-Spectral Scanner; Mexico. |
| Ano: 2005 |
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| Blain,Gabriel C.; Camargo,Marcelo B. P. de. |
| This study aimed to describe the probabilistic structure of the annual series of extreme daily rainfall (Preabs), available from the weather station of Ubatuba, State of São Paulo, Brazil (1935-2009), by using the general distribution of extreme value (GEV). The autocorrelation function, the Mann-Kendall test, and the wavelet analysis were used in order to evaluate the presence of serial correlations, trends, and periodical components. Considering the results obtained using these three statistical methods, it was possible to assume the hypothesis that this temporal series is free from persistence, trends, and periodicals components. Based on quantitative and qualitative adhesion tests, it was found that the GEV may be used in order to quantify the... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Extreme values; Adhesion tests; Time series. |
| Ano: 2012 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-69162012000300014 |
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| Araújo,Gleyce K. D.; Rocha,Jansle V.; Lamparelli,Rubens A. C.; Rocha,Agmon M.. |
| The search for low subjectivity area estimates has increased the use of remote sensing for agricultural monitoring and crop yield prediction, leading to more flexibility in data acquisition and lower costs comparing to traditional methods such as census and surveys. Low spatial resolution satellite images with higher frequency in image acquisition have shown to be adequate for cropland mapping and monitoring in large areas. The main goal of this study was to map the Summer crops in the State of Paraná, Brazil, using 10-day composition of NDVI SPOT Vegetation data for 2005/2006, 2006/2007 and 2007/2008 cropping seasons. For this, a supervised digital classification method with Parallelepiped algorithm in multitemporal RGB image composites was used, in order... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Remote sensing; Time series; Crop yield estimates. |
| Ano: 2011 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-69162011000400014 |
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| Amaro,André L. N.; Yanagi Junior,Tadayuki; Yanagi,Sílvia de N. M.; Ferraz,Gabriel A. E S.; Campos,Alessandro T.. |
| Abstract The aim of the present research was to propose a bioclimatic mapping to classify the thermal comfort and discomfort of rural workers within the state of Minas Gerais, considering historical and future scenarios. Monthly historical series (1976-2014) of minimum, mean and maximum temperature-humidity index (THI), determined through the values of air temperature (minimum, mean and maximum) and relative humidity from 48 weather stations located in the state of Minas Gerais were used to analyze the trends through Mann-Kendall and linear regression assays. The bioclimatic mapping of human comfort, obtained via geostatistical analysis, was developed as a function of the minimum, medium and maximum THI for the historical period (1976-2014) and future... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Human; Biometeorology; Human thermal comfort; THI; Time series. |
| Ano: 2018 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-69162018000200173 |
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| Puillat, Ingrid; Prevosto, Marc; Mercier, Herle; Thomas, S.. |
| In our time emerged the idea of a major environmental degradation, at both local and global scales, in the face of the recurrent human pollution. Consequently in the sake of a sustainable humanity development, of the ethic and of the ecology, the protection and the monitoring of our environment have become a major stake. Many scientific and technical tools contributed to improve the environmental knowledge, as helped remote and in situ observations, and forecast modeling. In situ environmental sensor systems have been designed to be increasingly sustainable even in a hostile environment such as the deep ocean. In a similar way, the infrastructures hosting those sensors are now thought and built to be permanent. In marine sciences these considerations gave... |
| Tipo: Text |
Palavras-chave: Time series; Marine data; Signal processing; Statistics. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00161/27259/25468.pdf |
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| Mcclintock, Brett T.; Langrock, Roland; Gimenez, Olivier; Cam, Emmanuelle; Borchers, David L.; Glennie, Richard; Patterson, Toby A.; Coulson, Tim. |
| Ecological systems can often be characterised by changes among a finite set of underlying states pertaining to individuals, populations, communities or entire ecosystems through time. Owing to the inherent difficulty of empirical field studies, ecological state dynamics operating at any level of this hierarchy can often be unobservable or ‘hidden’. Ecologists must therefore often contend with incomplete or indirect observations that are somehow related to these underlying processes. By formally disentangling state and observation processes based on simple yet powerful mathematical properties that can be used to describe many ecological phenomena, hidden Markov models (HMMs) can facilitate inferences about complex system state dynamics that might otherwise... |
| Tipo: Text |
Palavras-chave: Behavioural ecology; Community ecology; Ecosystem ecology; Hierarchical model; Movement ecology; Observation error; Population ecology; State-space model; Time series. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00655/76692/77831.pdf |
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| Registros recuperados: 76 | |
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