Piecewise direct standardization

Piece goods, detersive systems for, <5 413t Piecewise Direct Standardization, 6 67 Pierce s Disease, 26 309... 

Standardizing the spectral response is mathematically more complex than standardizing the calibration models but provides better results as it allows slight spectral differences - the most common between very similar instruments - to be corrected via simple calculations. More marked differences can be accommodated with more complex and specific algorithms. This approach compares spectra recorded on different instruments, which are used to derive a mathematical equation, allowing their spectral response to be mutually correlated. The equation is then used to correct the new spectra recorded on the slave, which are thus made more similar to those obtained with the master. The simplest methods used in this context are of the univariate type, which correlate each wavelength in two spectra in a direct, simple manner. These methods, however, are only effective with very simple spectral differences. On the other hand, multivariate methods allow the construction of matrices correlating bodies of spectra recorded on different instruments for the above-described purpose. The most frequent choice in this context is piecewise direct standardization... 

MTBF mean time between failure PDS piecewise direct standardization... 

This method assumes that the differences between the primary and secondary instruments follow a simple linear relationship. In fact, the differences may be much more complex, in which case more-advanced methods like piecewise direct standardization (PDS) may be more useful. 

The goal of methods that standardize instrument response is to find a function that maps the response of the secondary instrument to match the response of the primary instrument. This concept is used in the statistical analysis procedure known as Procrustes analysis [97], One such method for standardizing instrument response is the piecewise direct standardization (PDS) method, first described in 1991 [98,100], PDS was designed to compensate for mismatches between spectroscopic instruments due to small differences in optical alignment, gratings, light sources, detectors, etc. The method has been demonstrated to work well in many NIR assays where PCR or PLS calibration models are used with a small number of factors. 

P. J. Gemperline, J. H. Cho, P. K. Aldridge, and S. S. Sekulic, Appearance of Discontinuities in Spectra Transformed by the Piecewise Direct Instrument Standardization Procedure, Anal. Chem.,... 

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