Comparing sampling needs for variograms of soil properties computed by the method of moments and residual maximum likelihood

Geoderma ◽  
2007 ◽  
Vol 140 (4) ◽  
pp. 383-396 ◽  
Author(s):  
R. Kerry ◽  
M.A. Oliver
Keyword(s):  
Maximum Likelihood ◽  
Soil Properties ◽  
Method Of Moments ◽  
Residual Maximum Likelihood

Adjusting for fertility and competition in variety trials

2001 ◽  
Vol 136 (2) ◽  
pp. 129-140 ◽  
Author(s):  
M. DURBAN ◽  
I. D. CURRIE ◽  
R. A. KEMPTON
Keyword(s):  
Maximum Likelihood ◽  
Sugar Beet ◽  
Regression Model ◽  
Mixed Model ◽  
Smoothing Spline ◽  
Fertility Trends ◽  
Residual Maximum Likelihood ◽  
Plot Yield ◽  
Plant Breeding Institute ◽  
Auto Regressive

A joint model for plot yield in response to fertility trends and interplot competition is described. The model combines the mixed model representation of a cubic smoothing spline to model fertility and a regression model with auto-regressive terms to model competition. Estimation is based on a generalization of residual maximum likelihood. The methods were applied to a series of 70 sugar beet trials conducted by the Plant Breeding Institute, Cambridge, UK, and the results summarized.

Use of residual maximum likelihood to evaluate accuracy of two NIRS calibration procedures, relative to Kjeldahl, for determining nitrogen concentration of soybeans

1991 ◽  
Vol 71 (2) ◽  
pp. 385-392 ◽  
Author(s):  
G. B. Schaalje ◽  
H. -H. Mündel
Keyword(s):  
Maximum Likelihood ◽  
Near Infrared ◽  
Nitrogen Concentration ◽  
Principal Component Regression ◽  
Principal Component ◽  
Field Trials ◽  
Near Infrared Reflectance ◽  
Residual Maximum Likelihood ◽  
Maximum Likelihood Procedure ◽  
Calibration Methods

The accuracy of estimates of plant properties based on near-infrared reflectance spectroscopy (NIRS) varies with many factors including the biological material in question and the method used to calibrate the NIRS instrument. This study investigated the accuracy, relative to Kjeldahl analysis, of NIRS analysis based on two calibration methods in estimating nitrogen concentration of four stages and/or parts of soybean (Glycine max (L.) Merr.) plants. Samples of whole top growth at anthesis, whole top growth at maturity, whole top growth at maturity excluding seeds, and seeds were obtained from two field trials and one phytotron experiment. Two Kjeldahl determinations of nitrogen concentration were obtained for each sample, as well as reflectance values at each of 19 infrared wavelengths, using a Technicon InfraAlyser 400R. Different subsets of the sample data were used for calibration and assessment of accuracy. The instrument was calibrated using stepwise multiple linear regression (SMLR) and principal component regression (PCR). The residual maximum likelihood procedure was useful in showing that NIRS estimates based on either SMLR or PCR were at least as accurate as Kjeldahl estimates for all stages and/or parts except whole top growth at maturity excluding seeds. Key words: Calibration, principal component regression, stepwise regression

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