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Populations Structuring of Near Infrared Spectra and Modified Partial Least Squares Regression
Author(s) -
Shenk John S.,
Westerhaus Mark O.
Publication year - 1991
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1991.0011183x003100060034x
Subject(s) - standard error , mathematics , calibration , forage , population , hordeum vulgare , statistics , biology , hay , partial least squares regression , poaceae , agronomy , zoology , analytical chemistry (journal) , chemistry , chromatography , demography , sociology
The computer programs CENTER and SELECT have been presented as a way to establish population boundaries and choose samples for near infrared calibrations. This study was conducted to evaluate calibrations derived on samples chosen by CENTER and SELECT from broad groups of hay, haylage, corn ( Zea mays L.), wheat ( Triticnm aestivum L.), and barley ( Hordeum vulgare L.) samples. Population boundaries were established with a maximum standardized H distance from the average spectrum of 3.0. Every fifth sample was reserved for equation validation. Calibration samples were selected with a minimum standardized H distance between samples of 0.6. Forage samples were found to have more diverse spectra and chemistry than grain samples. Average r 2 values were smaller, numbers of eigenvectors were larger, and standard deviations of laboratory reference values were larger for forages than for grains. The standard error of performance (SEP) for all samples and SEP for samples chosen by SELECT with a limit of 0.6 were similar for four of five products. Calibrations were developed using five different math treatments with and without multiplicafive scatter correction (De‐trend). First derivative was the best math treatment for protein in all products. Second derivative was best for acid‐detergent fiber (ADF) in forage products, but no single math treatment was superior for ADF in grain products. De‐trend improved SEP in 28 of 50 calibrations.