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Agricultural yield expectations under climate change - a Bayesian approach AgEcon
Krause, Jette.
In the years to come, German wheat, corn and aggregated cereal yields can be expected to show growing deviations from a linearly increasing trend. This results from the Bayesian Updating approach I apply to agricultural yield data. The updating procedure is carried out on a set of hypotheses on yield development, which are weighted in the light of yield data from 1950 through 2006. All hypotheses share the assumption of a linear yield trend with normally distributed variance of actual data from this trend, but differ in regard to possible future developments. The set of hypotheses allows for both the trend and the variance of data to stay unchanged, increase or decrease by 20 per cent from one period to the next. As a result, yield expectations converge to...
Tipo: Conference Paper or Presentation Palavras-chave: Bayesian updating; Agricultural yields; Expectation; Risk; Climate change; Trend; Variance; Volatility; Crop Production/Industries; Environmental Economics and Policy.
Ano: 2007 URL: http://purl.umn.edu/9273
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Analisis de tendencia en el modelo autoregresivo bajo innovaciones con distribuciones normal y otras Colegio de Postgraduados
Maza Cantellano, Pablo.
Se analiza la tendencia en el modelo autorregresivo. Se propone el nivel de tendencia y se observa si las pruebas de Mann-Kendall y el coeficiente de correlación de Pearson la detectan, variando el tamaño de muestra, el valor del término autorregresivo, el nivel de significancia y el tipo de distribución que siguen las innovaciones, la cual puede ser Exponencial, Pareto, de Valor Extremo Generalizado Tipo I o Normal. El proceso es aplicado a datos simulados sin transformar y a datos transformados con sus rangos. Los resultados sugieren que cuando se utiliza la transformación del rango se obtiene la mejor potencia, aunque no existen notables diferencias entre ambas pruebas puede decirse que la mejor es la prueba de Mann-Kendall, dado que es menos...
Tipo: Tesis Palavras-chave: Tendencia; Autorregresivo; Mann-Kendall; Coeficiente de correlación de Pearson; Transformación del rango; Maestría; Estadística; Trend; Autorregressive; Mann-Kendall; Pearson correlation coefficient; Range transformation.
Ano: 2008 URL: http://hdl.handle.net/10521/1506
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Analyse des tendances des séries temporelles de la concentration en azote minéral dissous dans les trois principaux estuaires de la façade Manche-Atlantique ArchiMer
Gailhard, Isabelle.
Estuaries are areas which, from their structure, their fonctioning, and their localisation, are subject to significant contribution of nutrients. One of the objectif of the RNO, the French network for coastal water quality monitoring, is to assess the levels and trends of nutrient concentrations in estuaries. A linear model was used in order to describe and to explain the total dissolved nitrogen concentration evolution in the three most important estuaries on the Chanel-Atlantic front (Seine, Loire and Gironde). As a first step, the selection of a reliable data set was performed. Then total dissolved nitrogen evolution schemes in estuary environment were graphically studied, and allowed a resonable choice of covariables. The salinity played a major role...
Tipo: Text Palavras-chave: Nutriments; Estuaire; Loire; Seine; Gironde; Schéma de dilution; Modèle linéaire; Tendance; Nutrients; Estuary; Seine; Loire; Gironde; Dilution schema; Linear mode1; Trend.
Ano: 2000 URL: http://archimer.ifremer.fr/doc/00079/19070/16665.pdf
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Antarctic icebergs: A significant natural ocean sound source in the Southern Hemisphere ArchiMer
Matsumoto, Haru; Bohnenstiehl, Delwayne R.; Tournadre, Jean; Dziak, Robert P.; Haxel, Joseph H.; Lau, T. -k. A.; Fowler, Matt; Salo, Sigrid A..
In late 2007, two massive icebergs, C19a and B15a, drifted into open water and slowly disintegrated in the southernmost Pacific Ocean. Archived acoustic records show that the high-intensity underwater sounds accompanying this breakup increased ocean noise levels at mid-to-equatorial latitudes over a period of ∼1.5 years. More typically, seasonal variations in ocean noise, which are characterized by austral summer-highs and winter-lows, appear to be modulated by the annual cycle of Antarctic iceberg drift and subsequent disintegration. This seasonal pattern is observed in all three Oceans of the Southern Hemisphere. The life cycle of Antarctic icebergs affects not only marine ecosystem but also the sound environment in far-reaching areas and must be...
Tipo: Text Palavras-chave: Antarctica; Iceberg; Ocean noise; Seasonality; Trend.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00205/31613/30035.pdf
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Characteristics of Price Fluctuation of Agricultural Products in China AgEcon
Guo, Xiao-hui; Ge, Dang-qiao.
This paper introduces the basic trend of the price of agricultural products in China, and analyzes the causation of rigid rise of agricultural product price. We also study on the fluctuation characteristics of the prices of Chinese and classification agricultural products.
Tipo: Thesis or Dissertation Palavras-chave: Agricultural product price; Fluctuation characteristics; Trend; China; Agricultural and Food Policy; Demand and Price Analysis; Food Consumption/Nutrition/Food Safety; Marketing; Research Methods/ Statistical Methods; Resource /Energy Economics and Policy.
Ano: 2009 URL: http://purl.umn.edu/53515
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Generalized least squares for trend estimation of summarized dose–response data AgEcon
Orsini, Nicola; Bellocco, Rino; Greenland, Sander.
This paper presents a command, glst, for trend estimation across different exposure levels for either single or multiple summarized case–control, incidence-rate, and cumulative incidence data. This approach is based on constructing an approximate covariance estimate for the log relative risks and estimating a corrected linear trend using generalized least squares. For trend analysis of multiple studies, glst can estimate fixed- and random-effects metaregression models.
Tipo: Journal Article Palavras-chave: Glst; Dose–response data; Generalized least squares; Trend; Meta-analysis; Metaregression; Research Methods/ Statistical Methods.
Ano: 2006 URL: http://purl.umn.edu/117556
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Have Biotech Seeds Increased Maize Yields? AgEcon
Xu, Zheng; Hennessy, David A.; Moschini, GianCarlo.
Corn yield is determined by soils, weather, seed used and other technology choices. Global population and per capita income growth trends as well as demand from the energy sector have placed great stress on cropland use. Global cropland acres and/or yield per acre will need to increase. Whether new seed technologies have enhanced corn yield is a controversial issue. We study U.S. county corn yields 1964-2008, controlling for location effects, fertilization technologies and weather. We find evidence that trend yield growth has been fastest in the Central Corn Belt, genetic modification technologies have increased trend yield, and this increase has been largest in the Central Corn Belt.
Tipo: Conference Paper or Presentation Palavras-chave: Biotechnology; Corn Yield; Trend; Regional Effects; Weather; Fertilization.; Crop Production/Industries; Industrial Organization; Research and Development/Tech Change/Emerging Technologies; L65; Q16.
Ano: 2010 URL: http://purl.umn.edu/61303
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Les surcotes et les décotes marines à Brest, étude statistique et évolution ArchiMer
Bouligand, R; Pirazzoli, Pa.
Sea surges (positive or negative) are short-period events (several hours to several days) among the most extreme oceanic phenomena resulting from climatic variability. A statistical study of hourly tide-gauge records at Brest does not allow any clear trend in long-term variations of these extreme sea levels to be detected. However, the frequency of extreme positive sea surges has increased recently (1953-1994), whereas extreme and sub-extreme negative sea surges has decreased. Such trends for the highest values strengthen the prevalence of positive sea surges over negative ones. The general evolution appears to be organised around several time scales, with a strong interannual variability superimposed on periods of amplification or regression of decennial...
Tipo: Text Palavras-chave: Niveau marin; Surcotes et décotes marines; Fréquence; Évolution; Brest; Sea level; Positive and negative sea surges; Frequency; Trend; Brest.
Ano: 1999 URL: http://archimer.ifremer.fr/doc/00325/43617/43918.pdf
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Market Instability in a New Era of Corn, Soybean, and Wheat Prices AgEcon
Irwin, Scott H.; Good, Darrel L..
Tipo: Journal Article Palavras-chave: Grain; Price; Increase; Trend; Demand and Price Analysis; Marketing; Q11; Q13.
Ano: 2009 URL: http://purl.umn.edu/94694
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MODELOS DE SÉRIES TEMPORAIS APLICADOS À SÉRIE DOS ÍNDICES DE PREÇOS AO CONSUMIDOR NA REGIÃO DE LAVRAS, MG, NO PERÍODO DE 1992 A 1999 AgEcon
Silva, Roberta Bessa Veloso; Ferreira, Daniel Furtado; Safadi, Thelma.
This piece of work was carried out objectifying to adjust the time series models to the series of price indexes for the consumer ( PIC ) of Lavras MG. It aimed at verifying the occurrence of differences in trend as for the period which preceeded, as well as for the one which succeeded the Plano Real, and if there was a simple linear trend along with Plano Real ( 1994-1999 ) as well as if any seasonality occurred. It also objectified to comparing the series of both Lavras and the Federal District. It was verified that there was no trend along the whole series, nor there was any seasonality, notwithstanding the fact that a level change occurred, which was characterized as an intervention, rather than a trend. It was necessary to fit a model featuring an...
Tipo: Journal Article Palavras-chave: Price index to the consumer; Trend; Seasonality; Forecast.
Ano: 2000 URL: http://purl.umn.edu/43355
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Variabilidade mesoclimática da chuva no norte e noroeste do estado do Rio de Janeiro. Repositório Alice
LIMA, E. de P.; MINUZZI, R. B.; PEREIRA, F. A.; LYRA, G. B..
Resumo: A chuva é um dos elementos climáticos mais importantes. Na quantidade e no período adequado pode trazer benefícios para, por exemplo, a agricultura, mas em situações adversas pode causar prejuízos, como inundações e deslizamentos de terra. Nesse sentido, este estudo analisou a variabilidade climática da altura pluviométrica sazonal nas mesorregiões Norte e Noroeste do estado do Rio de Janeiro. Foram utilizados dados trimestrais de chuva de onze estações hidrológicas. Os métodos da Análise de Regressão e, de Kendall foram utilizados para testar a tendência da altura pluviométrica sazonal. Os resultados mostraram que no verão e inverno foram observadas as maiores e menores tendências significativas da altura pluviométrica, respectivamente. Abstract:...
Tipo: Resumo em anais de congresso (ALICE) Palavras-chave: Climatologia; Estações do ano; Tendência; Climatology; Seasons; Trend.
Ano: 2014 URL: http://www.alice.cnptia.embrapa.br/handle/doc/996171
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Weather Effects on Trend, Variance and Distribution of Crop Yield AgEcon
Yu, Tian; Babcock, Bruce A..
Favorable weather conditions for dryland crop production, including a proper amount of heat and rainfall during the growing season, are critical factors determining yield outcomes. Weather conditions however, are randomly distributed across regions and over time, thus influencing the temporal and geographical patterns of measured crop yield. Failure to account for weather factors when estimating crop yield distributions, time trends or productivity gains can lead to spurious conclusions regarding technology improvement, yield risk and skewness of yield. This paper addresses some limitations in the literature that result from not taking into account weather, and proposes an approach to incorporate weather into modeling yield.
Tipo: Conference Paper or Presentation Palavras-chave: Corn yield; Distribution; Trend; Yield risk; Agricultural Finance.
Ano: 2010 URL: http://purl.umn.edu/60908
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World and regional trends in maize production, productivity and demand Thai Agricultural
Harrington, L.W..
4 ill., 11 tables
Palavras-chave: Corn; Maize; Production; Productivity; Demand; Supply; Utilization; Facts; Trend; ข้าวโพด; การผลิต; ผลผลิต; อุปสงค์; อุปทาน; แนวโน้ม.
Ano: 1989 URL: http://anchan.lib.ku.ac.th/agnet/handle/001/4322
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