Hello Emmanuelle,

The PCA module featured in the current version of Athena does not calculate 
SPOIL values. This is actually one of the things that Bruce Ravel has listed in 
his current "Demeter/Athena/Artemis to do list" of his website, see section 

For SPOIL calculations I recommend you to use the PCA/TT module of Sixpack. 
According to Sam Webb, the latest Sixpack (version 1.4) employs a new/different 
PCA algorithm from the scikit-learn Python package. Using personal data set, I 
found that the PCA/target transformation results obtained from the new Sixpack 
v 1.4 are different from those obtained from an older version (v 1.2.10). It 
would be interesting to know whether other Sixpack users have come up to the 
same conclusion.

The SPOIL values obtained from a homemade code, following the method detailed 
in the Malinowski 1978 reference article, are very similar to SPOIL values 
reported in the Malinowski 1978 paper using mass spec data set from Ritter et 
al. 1976, and also SPOIL values obtained from an old Sixpack version (v 1.2.10) 
using personal xafs data set. Therefore, if you have installed on your PC the 
latest Sixpack version (v 1.4), you may want to select, in the menu bar on top 
of PCA/TT Sixpack module, "Rotation" then "Use Old PCA" to calculate SPOIL 
values. The calculated SPOIL values will be then equal to those obtained from 
the previous Sixpack versions.

Good luck,


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