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United States Department of Agriculture

Agricultural Research Service

Title: Statistical Criteria to Evaluate Ptf Accuracy and Reliability

Author
item Schaap, Marcel - U.C. RIVERSIDE, CA

Submitted to: Development of Pedotransfer Functions in Soil Hydrology
Publication Type: Book / Chapter
Publication Acceptance Date: December 2, 2003
Publication Date: N/A
Repository URL: http://www.ars.usda.gov/SP2UserFiles/Place/53102000/pdf_pubs/P2018.pdf

Interpretive Summary: Direct measurement of hydraulic properties is often difficult, expensive and time-consuming. Pedotransfer functions (PTFs) offer a means to estimate soil hydraulic properties based on predictors like texture, bulk density and other soil variables. The chapter is part of a book on the background and use of PTFs. The chapter contribute to a wider understanding of the methods to develop and especially evaluate PTFs. The intended audience is mainly those who develop PTFs, but also interested users.

Technical Abstract: Several statistical criteria are available to evaluate and quantify the potential usefulness of PTFs in making accurate and reliable estimates of soil hydraulic properties. The second chapter deals with three closely related terms: optimization, accuracy, and reliability. Optimization criteria are the objective functions used to calibrate empirical parameters in PTFs. Accuracy criteria relate to the statistical methods used to test the performance of indirect methods, preferably using data distinct from those used for calibration. Uncertainty estimates provide information about the probability distribution of estimated hydraulic quantities.

Last Modified: 9/2/2014
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