Metrohm Vision Manual User Manual
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PLS equation validation is a procedure that helps to establish the optimum number of factors
for the equation. This is done by finding a minimum of the PRESS value.
Vision offers four validation methods:
•
Self Validation - the equation is developed from the training set of spectra, and the validation
set is predicted. The PRESS value is calculated as the sum of squared residuals.
•
Cross Validation - a moving segment is removed from the training set and predicted by the
equation developed from the remaining samples. In full cross validation only one sample is
removed at a time. The PRESS value is calculated as the sum of squared residuals.
•
Leverage Validation - the training set itself is predicted. The residuals are then corrected by
the leverage factor. The PRESS value is calculated as the sum of squared residuals.
•
External Validation - allows the use of selected samples from another product as a prediction
set. The PRESS value is calculated as the sum of squared residuals.
4.
Click on OK when done to proceed with PLS calculations.