Hello, I'm new to PCA analyses with my XANES data and started with the D-Athena. Are the TT Coefficients similar to a SPOIL value (SPOIL values are calculated as the quotient of real error in the target divided by the error in the data matrix)? I've seen that one researcher relied on SPOIL values <1 for populating his LCF models. The TT values of some of my standards I know to be unreasonable (e.g. reduced standard used for TT of an oxidized sample) gave me negative values. Should I only accept values >0. Thanks for your time. Respectfully, Bradley W. Miller, Ph.D. Post Doctoral Fellow Oak Ridge Institute for Science and Education U. S. Environmental Protection Agency National Risk Management Research Laboratory Land Remediation and Pollution Control Division 5995 Center Hill Avenue, Cincinnati, OH 45224-1702 Office: (513) 487-2889 Miller.BradleyW@epa.gov Fax: (513) 569-7879 www.epa.gov www.tinyurl.com/bwmiller The great tragedy of Science—the slaying of beautiful hypothesis by an ugly fact.— Thomas H. Huxley Views or Opinions expressed in this email is solely representative of the sender and does not represents those of the EPA or any other agency.