re: Question for Statistics Gurus

quote:

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need to know a little bit about the design of the experiment first.

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This is using FT-NIR spectroscopy as a quantitative technique. You take a collection of various samples and collect the absorbance spectra of it. Then you obtain the attribute values from a different reference method. You input these reference values into the computer, and it looks for a correlative function via PLS regression between the reference value and the integrated spectrum area based on the parameters you put in (wavelength regions, mathematical preproccessing of them, etc)

Now you have a function correlating spectra signal to reference value, now that remains is to test it for accuracy. The first is a cross validation test, where one of the spectra in the calibration is excluded and tested with the calibrations of the other spectra, repeated for all calibration samples.

That is a preliminary test.

The final test is showing results of the model to spectra not contained in the calibration spectra at all.

All graphics I have shown prior to this point have been of the difference of predicted values and actual values. While the model data itself isn't normally distributed, the residuals are