Can the output of plsregress be used to calculate Q residuals and T2 for new X data
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Assume we have spectral data xcal, ycal, xval, yval where
xcal is mxn : m spectra, or observations, of a sample, n wavelengths per spectrum
ycal is mx1 : m concentrations of the sample corresponding to the m observations in xcal
xval is 1xn : 1 new spetrum or new observation of the sample (ie, not a member of xcal)
yval is 1x1 : 1 new concentration of the sample corresponding to the observation in xval
assuming m>n and ncomp<n and xcal0 is xcal with its mean subtracted,
xcal0 = xcal - ones(m,1)*mean(xcal)
[XL,YL,XS,YS,BETA,PCTVAR,MSE,STATS] = PLSREGRESS(xcal,ycal,ncomp);
Can be used to compute Q residuals, or the rowwise sum of squares of the STATS.XResiduals matrix
and
STATS.T2, is the Hotelling T^2 value
for each of the m observations in xcal
Q residuals and T2 values can be used to determine if the observations in xcal are outliers
Can the outputs of plsregress as described above be used to compute a Q residual and a T^2 value for the single observation in xval to determine if it seems to be an outlier with respect to xcal?
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