SABIIA - Sistema Aberto e Integrado de Informação em Agricultura (Sabiia)

Response of Arctic Freshwater to the Arctic Oscillation in Coupled Climate Models

Soudant, Dominique; Beliaeff, Benoit; Thomas, G.

Classical regression analysis can be used to model time series. However, the assumption that model parameters are constant over time is not necessarily adapted to the data. In phytoplankton ecology, the relevance of time-varying parameter values has been shown using a dynamic linear regression model (DLRM). DLRMs, belonging to the class of Bayesian dynamic models, assume the existence of a non-observable time series of model parameters, which are estimated on-line, i.e. after each observation. The aim of this paper was to show how DLRM results could be used to explain variation of a time series of phytoplankton abundance. We applied DLRM to daily concentrations of Dinophysis cf. acuminata, determined in Antifer harbour (French coast of the English...

Tipo: Text

Palavras-chave: Phytoplankton; Dinophysis; Time series; Regression; Dynamic; Bayesian.

Ano: 1997

URL: http://archimer.ifremer.fr/doc/00337/44784/44490.pdf

Research of quality indices for cold-smoked salmon using a stepwise multiple regression of microbiological counts and physico-chemical parameters

Cornish, Sam B.; Kostov, Yavor; Johnson, Helen L.; Lique, Camille.

The freshwater content (FWC) of the Arctic Ocean is intimately linked to the stratification—a physical characteristic of the Arctic Ocean with wide relevance for climate and biology. Here, we explore the relationship between atmospheric circulation and Arctic FWC across 12 different Coupled Model Intercomparison Project Phase 5 control run simulations. Using multiple lagged regression, we seek to isolate the linear response of Arctic FWC to a step change in the strength of the Arctic Oscillation (AO), as well as the second and third orthogonal modes of SLP variability over the Arctic domain. There is broad agreement amongst models that a step change to a more anticyclonic AO leads to an increase in Arctic FWC, with an e-folding timescale of five to ten...

Tipo: Text

Palavras-chave: Arctic; Arctic Oscillation; Freshwater; Statistical techniques; Regression.

Ano: 2020

URL: https://archimer.ifremer.fr/doc/00601/71270/69668.pdf

Leroi, Francoise; Joffraud, Jean-jacques; Chevalier, Frederique; Cardinal, Mireille.

Aims: The aim of the study was to assess the relationships between the remaining shelf-life (RSL) of cold-smoked salmon and various microbiological and physico-chemical parameters, using a multivariate data analysis in the form of stepwise forward multiple regression. Methods and Results: Thirteen batches of French cold-smoked salmon were analysed weekly during vacuum-packed storage at 5 degreesC for their lipid, water, salt, phenol, pH, total volatile basic nitrogen (TVBN) and trimethylamine contents, total psychrotrophic count, lactic acid bacteria, lactobacilli, B. thermosphacta, Enterobacteriaceae and yeast counts. At the sensory rejection time, the flora was dominated by lactobacilli, lactobacilli/Enterobacteriaceae or Carnobacteria/B. thermosphacta....

Tipo: Text

Palavras-chave: Microbiological; Parameters; Regression; Cold smoked salmon.

Ano: 2001

URL: http://archimer.ifremer.fr/doc/2001/publication-609.pdf

Uncertainties associated with in situ high-frequency long-term observations of suspended particulate matter concentration using optical and acoustic sensors

Relation between higher heating value and elemental and mineral biomass plant components

Fettweis, Michael; Riethmüller, Rolf; Verney, Romaric; Becker, Marius; Backers, Joan; Baeye, Matthias; Chapalain, Marion; Claeys, Styn; Claus, Jan; Cox, Tom; Deloffre, Julien; Depreiter, Davy; Druine, Flavie; Flöser, Götz; Grünler, Steffen; Jourdin, Frédéric; Lafite, Robert; Nauw, Janine; Nechad, Bouchra; Röttgers, Rüdiger; Sottolichio, Aldo; Van Engeland, Tom; Vanhaverbeke, Wim; Vereecken, Hans.

Measurement of suspended particulate matter concentration (SPMC) spanning large time and geographical scales have become a matter of growing importance in recent decades. At many places worldwide, complex observation platforms have been installed to capture temporal and spatial variability over scales ranging from cm (turbulent regimes) to whole basins. Long-term in situ measurements of SPMC involve one or more optical and acoustical sensors and, as the ground truth reference, gravimetric measurements of filtered water samples. The estimation of SPMC from optical and acoustical proxies generally results from the combination of a number of independent calibration measurements, as well as regression or inverse models. Direct or indirect measurements of SPMC...

Tipo: Text

Palavras-chave: Suspended particulate matter; Measurement uncertainty; Regression; Optical and acoustical sensors.

Ano: 2019

URL: https://archimer.ifremer.fr/doc/00510/62132/66364.pdf

PFB - Pesquisa Florestal Brasileira

Protásio, Thiago de Paula; Bufalino, Lina; Tonoli, Gustavo Henrique Denzin; Couto, Allan Motta; Trugilho, Paulo Fernando; Guimarães Júnior, Mário.

The aims of this work were to evaluate the correlation, to adjust and select simple and multiple linear statistical models between elemental components (carbon, hydrogen and oxygen) and ash content with higher heating value for plant biomass; to use the principle components analysis for the creation of an energetic development index and to adjust a linear model between energetic development index and higher heating value. Eight types of biomass were used. Three linear and nine multiple statistical models were adjusted. The best models were selected based on the significance of coefficients, adjusted determination coefficient, estimative standard error, coefficient of variation, linearity of parameters, normality, presence of heterocedasticity and lack of...

Growth curves of meat-producing mammals by von Bertalanffy’s model

Palavras-chave: Modeling; Regression; Correlation; Selection Modelagem; Regressão; Correlação; Seleção.

Ano: 2011

URL: http://pfb.cnpf.embrapa.br/pfb/index.php/pfb/article/view/200

PAB

Fernandes,Felipe Augusto; Fernandes,Tales Jesus; Pereira,Adriele Aparecida; Meirelles,Sarah Laguna Conceição; Costa,Adriano Carvalho.

Abstract: The objective of this work was to evaluate how the parameterization and the application of different allometric values affect the obtention of the most adequate fit of von Bertalanffy’s model, in the description of the growth curve of meat-producing mammals (bovine, pigs, rabbits, and sheep). Among the nonlinear models, von Bertalanffy’s has been very often applied in several areas, with different parameterizations. This model has been commonly used with an allometric value of m = 2/3; however, for mammals, it is believed that this value can be m = 3/4. The analyzed data referring to the mass of meat-producing mammals according to their age were obtained from research institutions and from the literature. The results showed that von Bertalanffy’s...

Lysine and arginine requirements of Salminus brasiliensis

Palavras-chave: Allometry; Modeling; Nonlinear model; Parameterization; Regression.

Ano: 2019

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-204X2019000104307

PAB

Dairiki,Jony Koji; Borghesi,Ricardo; Dias,Carlos Tadeu dos Santos; Cyrino,José Eurico Possebon.

The objective of this work was to determine the dietary lysine (DL) and dietary arginine (DA) requirements of dourado (Salminus brasiliensis), through dose-response trials using the amino acid profiles of whole carcasses as a reference. Two experiments were carried out in a completely randomized design (n=4). In the first experiment, groups of 12 feed-conditioned dourado juveniles (11.4±0.2 g) were stocked in 60 L cages placed in 300 L plastic indoor tanks in a closed circulation system. Fish were fed for 60 days on diets containing 1.0, 1.5, 2.0, 2.5, 3.0, or 3.5 % dietary lysine. In the second experiment, dourado juveniles (27.0±0.8 g) were fed for 60 days on semipurified diets containing arginine at 1.0, 1.5, 2.0, 2.5 or 3.0%, in similar conditions to...

An Appraisal of Beekeeping Activities among Beneficiaries and Non-Beneficiaries of Ekiti State Agricultural Credit Agency (ESACA) Scheme in Nigeria

Palavras-chave: Amino acid; Dose-response; Dourado; Regression.

Ano: 2013

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-204X2013000800032

Fakayode, S.B.; Babatunde, Raphael O.; Olowogbon, S.T.; Adesuyi, W.S..

The study examined beekeeping activities in Ekiti State, Nigeria. Specifically the study appraised the costs and returns structure of beekeeping activities by beneficiaries of the ESACA scheme, examined the constraints to beekeeping under the scheme and outside the scheme and identified factors that affect beekeeping under the scheme and outside the scheme. A total of 150 beekeeper households were selected; 75 households each for ESACA beneficiary and non-beneficiary respondents across communities popularly known for beekeeping in Ekiti state. Descriptive statistics, costs and returns, regression and Kruscalwallis analyses were employed for data analysis. Beekeeping was found to be more profitable under the ESACA scheme than outside the scheme with returns...

Causal inference with observational data

Palavras-chave: Kruscal-wallis; Costs and returns structure; Regression; Technical assistance; Crop Production/Industries; Livestock Production/Industries.

Ano: 2010

URL: http://purl.umn.edu/95785

Farmer-to-Consumer Direct Marketing: The Role of Customer Satisfaction Measurement for Service Innovations

Nichols, Austin.

Problems with inferring causal relationships from nonexperimental data are briefly reviewed, and four broad classes of methods designed to allow estimation of and inference about causal parameters are described: panel regression, matching or reweighting, instrumental variables, and regression discontinuity. Practical examples are offered, and discussion focuses on checking required assumptions to the extent possible.

Tipo: Article

Palavras-chave: Xtreg; Psmatch2; Nnmatch; Ivreg; Ivreg2; Ivregress; Rd; Lpoly; Xtoverid; Ranktest; Causal inference; Match; Matching; Reweighting; Propensity score; Panel; Instrumental variables; Excluded instrument; Weak identification; Regression; Discontinuity; Local polynomial; Research Methods/ Statistical Methods.

Ano: 2007

URL: http://purl.umn.edu/119292

Spiller, Achim; Zuhlsdorf, Anke; Mellin, Matthias.

The importance of direct marketing for high quality farm products has increased during the past few years. This paper analyses the impact of customer satisfaction and its driving forces for farmer- to-consumer direct marketing and is based on a customer survey in 33 organic and conventional on-farm stores in Germany. The results emphasise the role of store atmosphere and customer service as the main influencing factors on customer satisfaction.

Erratum and discussion of propensity–score reweighting

Palavras-chave: Direct Marketing; Customer satisfaction; Regression; Service Quality; Agribusiness; Marketing.

Ano: 2007

URL: http://purl.umn.edu/6607

Creating print-ready tables in Stata

Nichols, Austin.

Tipo: Article

Ano: 2008

URL: http://purl.umn.edu/122619

Lokshin, Michael; Sajaia, Zurab.

This article describes the new Stata command xml_tab, which outputs the results of estimation commands and Stata matrices directly into tables in XML format. The XML files can be opened with Microsoft Excel or OpenOffice Calc, or they can be linked with Microsoft Word files. By using XML, xml_tab allows Stata users to apply a rich set of formatting options to the elements of output tables.

Tipo: Article

Palavras-chave: Xml_tab; Estimates; Regression; Matrices; Xml; Excel; Word; Research Methods/ Statistical Methods.

Ano: 2008

URL: http://purl.umn.edu/122600

HEDGE DINÂMICOS: UMA EVIDÊNCIA PARA OS CONTRATOS FUTUROS BRASILEIROS

Bitencourt, Wanderci Alves; Silva, Washington Santos; Safadi, Thelma.

The farming sector is changing, growing and occupying a position of prominence in the economy. These transformations start to demand a bigger concern with the management of risks of the activity. In this direction, the contracts traded at BM&F had become efficient instruments in the reduction of the market risk, through an operation called hedge. However, there is still the necessity of improving of the econometrical techniques for the estimation of the optimal hedge ratio, therefore, it is observed in the brazilian literature that the majority of the works doesn’t consider some aspects of the behavior of the series of returns. Thus, the present work seeks to analyze two methods for the calculation of these hedge optimal ratio, the conventional model...

Tipo: Journal Article

Palavras-chave: Hedge optimal ratio; GARCH BEKK model; Regression.

Ano: 2006

URL: http://purl.umn.edu/43828

SIND BETRIEBSGEMEINSCHAFTEN WIRTSCHAFTLICHER ALS EINZELBETRIEBE?

Lips, Markus; Pulfer, Iris; Messer, Martin.

The influence of farming collectives on income per annual work unit (AWU) is investigated by means of regressions for three types of farms with animal husbandry. The effects are relatively small, and turn out differently for the three farm types. Whereas the effect is negative for the dairy farms (-1200 CHF), collective farming in the case of combined dairying/arable-crop farms and combined pig/poultry farms leads to a higher income (+900 and +500 CHF, respectively). The latter two farm types are characterised by at least two important production branches, unlike the dairy farms, which have just one. The result for the dairy farms, however, does not call the farming collective into question as a growth opportunity. The usual scale effects that can be...

What is Local and for What Foods Does it Matter?

Palavras-chave: Betriebsgemeinschaft; Einzelbetrieb; Einkommen; Regression; Schweiz; Farming collectives; Income; Individual farm; Switzerland; Agribusiness; Farm Management.

Ano: 2007

URL: http://purl.umn.edu/7617

Hu, Wuyang; Batte, Marvin T.; Woods, Timothy A.; Ernst, Stanley C..

Consumer demand for local foods has been increasing dramatically over the past several years. Many food producers and marketers are raising their capacity to incorporate local food. Revenue from local Farmers’ Market and Community Supported Agriculture has become a greater source of income particularly for small and medium-sized farms. This study answers two important questions related to local food that have not been sufficiently addressed before: what is the greatest distance food can travel and still be accepted by consumers as local and is "local" equally important across food categories. Using survey data from two states in the USA, this research found that consumers’ accepted food travel distance may be much shorter than what is generally...

Choosing an appropriate real-life measure of effect size: the case of a continuous predictor and a binary outcome

Palavras-chave: Distance; Food category; Importance rating; Local; Regression; Agribusiness; Agricultural and Food Policy; Consumer/Household Economics; Food Consumption/Nutrition/Food Safety; Marketing; Q13.

Ano: 2010

URL: http://purl.umn.edu/56326

Dislocation and Regression of the Role of Collective in Land Transfer

Conroy, Ronan M..

A case study of data on age and pregnancy is used to point up some morals for practicing data analysts, including the superiority of regression over t tests, exploratory scatterplot smoothing as a key method of checking form of relationship, and the value of logistic regression followed by adjust as a way of getting at the numbers of most interest.

Tipo: Journal Article

Palavras-chave: Adjust; Correlation; Logistic regression; Regression; Scatterplot smoothing; T tests; Research Methods/ Statistical Methods.

Ano: 2002

URL: http://purl.umn.edu/116011

Speaking Stata: Graphing model diagnostics

Xu, Wei; Yuan, Jingheng.

This paper expounds the origin of "collective" in the process of collective land transfer, and analyzes the dislocation phenomenon of the role of collective in the process of collective land transfer as follows: deviation of the role under the conflict of identity; offside of the role under the limitation of democratic construction; omission of the role under the segmentation of interests. In order to protect me legitimate rights of farmers, we should make the role of collective to revert on the basis of township government, farmer and collective, so that the role of collective is restored under the management of government; the role of collective reverts under the supervision of farmers; the role of collective returns under its own strengthening of...

Tipo: Journal Article

Palavras-chave: Land transfer; Role of collective; Dislocation; Regression; China; Agribusiness.

Ano: 2011

URL: http://purl.umn.edu/118289

Biomass and grain yield of oats by growth regulator

Cox, Nicholas J..

Plotting diagnostic information calculated from residuals and fitted values is a long-standard method for assessing models and seeking ways of improving them. This column focuses on the statistical mainstream defined by regression models for continuous responses, treated in a broad sense to include (for example) generalized linear models. After some comments on the history of such ideas (and even their anthropology and psychology), the commands available in official Stata are reviewed, and a modeldiag package is introduced. A detailed example on fuelwood yield from fallow areas in Nigeria illustrates a variety of general points and specific tips.

Tipo: Journal Article

Palavras-chave: Modeldiag; Anovaplot; Indexplot; Ofrtplot; Ovfplot; Qfrplot; Racplot; Rdplot; Regplot; Rhetplot; Rvfplot2; Rvlrplot; Rvpplot2; Graphics; Diagnostics; Regression; Generalized linear models; Analysis of variance; Research Methods/ Statistical Methods.

Ano: 2004

URL: http://purl.umn.edu/116273

AGRIAMBI

Marolli,Anderson; Silva,José A. G. da; Romitti,Marcos V.; Mantai,Rubia D.; Hawerroth,Maraisa C.; Scremin,Osmar B..

ABSTRACT The use of growth regulator in oats can reduce plant lodging with reflections in biomass and grain yield. The objective of the study was to determine the feasibility and efficiency of using Trinexapac-Ethyl regulator in the growth of white oat under different conditions of N-fertilizer and years favorable and unfavorable for cultivation. In this study, two experiments were conducted in the years 2011, 2012 and 2013, one for quantifying biomass production rate and the other for the determination of grain yield and lodging. The experimental design was randomized blocks with four replicates, in a 4 x 3 factorial scheme, for growth regulator doses (0, 200, 400 and 600 mL ha-1) and nitrogen doses (30, 90 and 150 kg ha-1), respectively. There is a...

Common factors method to predict the carcass composition tissue in kid goats

Palavras-chave: Avena sativa; Trinexapac-ethyl; Lodging; Nitrogen; Regression.

Ano: 2017

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662017000300163

R. Bras. Zootec.

Gomes,Helen Fernanda Barros; Gonçalves,Heraldo Cesar; Polizel Neto,Angelo; Cañizares,Gil Ignacio Lara; Roça,Roberto de Oliveira; Marques,Raquel Ornelas; Oliveira,Giuliana Micai de; Queiroz,Edicarlos Oliveira.

The objective of this work was to analyze the interrelations among weights and carcass measures of the longissimus lumborum muscle thickness and area, and of sternum tissue thickness, measured directly on carcass and by ultrasound scan. Measures were taken on live animals and after slaughter to develop models of multiple linear regression, to estimate the composition of shoulder blade, from selected variables in 89 kids of both genders and five breed groups, raised in feedlot system. The variables considered relevant and not redundant on the information they carry, for the common factor analysis, were used in the carcass composition estimate development models. The presuppositions of linear regression models relative to residues were evaluated, the...