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Registro Completo |
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Biblioteca(s): |
Embrapa Agricultura Digital. |
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Data corrente: |
25/04/2011 |
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Data da última atualização: |
08/07/2011 |
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Tipo da produção científica: |
Artigo em Periódico Indexado |
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Autoria: |
VIEIRA, S. R.; CARVALHO, J. R. P. de; PAZ GONZÁLEZ, A. |
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Afiliação: |
SIDNEY ROSA VIEIRA, IAC; JOSE RUY PORTO DE CARVALHO, CNPTIA; ANTONIO PAZ GONZÁLEZ, Universidade da Coruña, Espanha. |
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Título: |
Jack knifing for semivariogram validation. |
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Ano de publicação: |
2010 |
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Fonte/Imprenta: |
Bragantia, Campinas, v. 69, p. 97-105, 2010 |
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Idioma: |
Inglês |
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Notas: |
Suplemento. |
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Conteúdo: |
The semivariogram function fitting is the most important aspect of geostatistics and because of this the model chosen must be validated. Jack knifing may be one the most efficient ways for this validation purpose. The objective of this study was to show the use of the jack knifing technique to validate geostatistical hypothesis and semivariogram models. For that purpose, topographical heights data obtained from six distinct field scales and sampling densities were analyzed. Because the topographical data showed very strong trend for all fields as it was verified by the absence of a sill in the experimental semivariograms, the trend was removed with a trend surface fitted by minimum square deviation. Semivariogram models were fitted with different techniques and the results of the jack knifing with them were compared. The jack knifing parameters analyzed were the intercept, slope and correlation coefficient between measured and estimated values, and the mean and variance of the errors calculated by the difference between measured and estimated values, divided by the square root of the estimation variances. The ideal numbers of neighbors used in each estimation was also studied using the jack knifing procedure. The jack knifing results were useful in the judgment of the adequate models fitted independent of the scale and sampling densities. It was concluded that the manual fitted semivariogram models produced better jack knifing parameters because the user has the freedom to choose a better fit in distinct regions of the semivariogram. MenosThe semivariogram function fitting is the most important aspect of geostatistics and because of this the model chosen must be validated. Jack knifing may be one the most efficient ways for this validation purpose. The objective of this study was to show the use of the jack knifing technique to validate geostatistical hypothesis and semivariogram models. For that purpose, topographical heights data obtained from six distinct field scales and sampling densities were analyzed. Because the topographical data showed very strong trend for all fields as it was verified by the absence of a sill in the experimental semivariograms, the trend was removed with a trend surface fitted by minimum square deviation. Semivariogram models were fitted with different techniques and the results of the jack knifing with them were compared. The jack knifing parameters analyzed were the intercept, slope and correlation coefficient between measured and estimated values, and the mean and variance of the errors calculated by the difference between measured and estimated values, divided by the square root of the estimation variances. The ideal numbers of neighbors used in each estimation was also studied using the jack knifing procedure. The jack knifing results were useful in the judgment of the adequate models fitted independent of the scale and sampling densities. It was concluded that the manual fitted semivariogram models produced better jack knifing parameters because the user has the freedom to c... Mostrar Tudo |
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Palavras-Chave: |
Erro reduzido; Estacionaridade; Semivariograms; Stationarity. |
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Thesagro: |
Topografia. |
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Thesaurus Nal: |
Topography. |
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Categoria do assunto: |
-- |
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URL: |
https://ainfo.cnptia.embrapa.br/digital/bitstream/item/33101/1/Jack2.pdf
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Marc: |
LEADER 02167naa a2200229 a 4500
001 1886773
005 2011-07-08
008 2010 bl uuuu u00u1 u #d
100 1 $aVIEIRA, S. R.
245 $aJack knifing for semivariogram validation.$h[electronic resource]
260 $c2010
500 $aSuplemento.
520 $aThe semivariogram function fitting is the most important aspect of geostatistics and because of this the model chosen must be validated. Jack knifing may be one the most efficient ways for this validation purpose. The objective of this study was to show the use of the jack knifing technique to validate geostatistical hypothesis and semivariogram models. For that purpose, topographical heights data obtained from six distinct field scales and sampling densities were analyzed. Because the topographical data showed very strong trend for all fields as it was verified by the absence of a sill in the experimental semivariograms, the trend was removed with a trend surface fitted by minimum square deviation. Semivariogram models were fitted with different techniques and the results of the jack knifing with them were compared. The jack knifing parameters analyzed were the intercept, slope and correlation coefficient between measured and estimated values, and the mean and variance of the errors calculated by the difference between measured and estimated values, divided by the square root of the estimation variances. The ideal numbers of neighbors used in each estimation was also studied using the jack knifing procedure. The jack knifing results were useful in the judgment of the adequate models fitted independent of the scale and sampling densities. It was concluded that the manual fitted semivariogram models produced better jack knifing parameters because the user has the freedom to choose a better fit in distinct regions of the semivariogram.
650 $aTopography
650 $aTopografia
653 $aErro reduzido
653 $aEstacionaridade
653 $aSemivariograms
653 $aStationarity
700 1 $aCARVALHO, J. R. P. de
700 1 $aPAZ GONZÁLEZ, A.
773 $tBragantia, Campinas$gv. 69, p. 97-105, 2010
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Registro original: |
Embrapa Agricultura Digital (CNPTIA) |
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| Registros recuperados : 69 | |
| 22. |  | CRUVINEL, P. E.; MINATEL, E. R.; MUCHERONI, M. L.; VIEIRA, S. R.; CRESTANA, S. An automatic method based on image processing for measurements of drop size distribution from agricultural sprinklers. In: SIMPOSIO BRASILEIRO DE COMPUTACAO GRAFICA E PROCESSAMENTO DE IMAGENS, 9., out. 1996, Caxambu, MG. Anais do SIBGRAPI 96. Caxambu: SBC/UFMG, 1996. p. 39-46.| Biblioteca(s): Embrapa Instrumentação. |
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| 28. | | MIGUEL, F. R. M.; VIEIRA, S. R.; CHIBA, M. K.; GREGO, C. R.; SIQUEIRA, G. M. Correlação espacial entre a produtividade da cana-de-açúcar e atributos químicos do solo. In: CONGRESSO BRASILEIRO DE AGRICULTURA DE PRECISÃO, 4., 2010. Ribeirão Preto, SP. Anais... Ribeirão Preto, SP: ABEA, 2010. 4 p.| Tipo: Artigo em Anais de Congresso |
| Biblioteca(s): Embrapa Territorial. |
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| 30. | | CARVALHO, J. R. P. D.; VIEIRA, S. R.; GREGO, C. R. Comparação de métodos para ajuste de modelos de semivariograma da precipitação pluvial anual. Revista Brasileira de Engenharia Agrícola e Ambiental, Campina Grande, v. 13, n. 4, p. 443-448, 2009. v. 13, n. 4,| Tipo: Artigo em Periódico Indexado | Circulação/Nível: B - 1 |
| Biblioteca(s): Embrapa Territorial. |
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| 33. | | GREGO, C. R.; RABELLO, L. M.; BRANCALIÃO, S. R.; VIEIRA, S. R.; OLIVEIRA, A. DE. Geoestatística aplicada a condutividade elétrica do solo e altitude do solo cultivado com cana-de-açúcar. In: INAMASU, R. Y.; NAIME, J. de M.; RESENDE, A. V. de; BASSOI, L. H.; BERNARDI, A. de C. (Ed.). Agricultura de precisão: um novo olhar. São Carlos, SP: Embrapa Instrumentação, 2011. p. 245-248| Tipo: Capítulo em Livro Técnico-Científico |
| Biblioteca(s): Embrapa Instrumentação; Embrapa Territorial. |
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| 38. | | SARVAS, F. de O. C.; VIEIRA, S. R.; CASTRO, O. M. de C.; BARBOSA, C. C. Curvas de Retencao de Agua, por Tensiometria, para dois Solos da Regiao de Alfenas (MG). Pesquisa Agropecuaria Brasileira, Brasilia, v.27, n.6, p.893-900, jun.1992| Biblioteca(s): Embrapa Unidades Centrais. |
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| Registros recuperados : 69 | |
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