[Ifeffit] Linear Combination Fitting in Athena-

[Skya Fawcett]

I'm doing linear combination fits using 10 standards total, and choosing
to use at most 3 or 4 standards in the fit. The problem is that depending
on which I choose, 3 or 4, the results vary significantly. Often one
standard will show up in one fit using at most 3 standards and not in a
fit using at most 4 standards. For example:

Unknown A:

Fit using at most 3 standards
Standard 1= 0.213
Standard 2= 0.374
Standard 3= 0.413

Fit using at most 4 standards
Standard 1= 0.282
Standard 2= 0.269
Standard 4= 0.102
Standard 5= 0.346

Unknown B:

Fit using at most 3 standards
Standard 1= 0.278
Standard 2= 0.745

Fit using at most 4 standards
Standard 2= 0.694
Standard 3= 0.117
Standard 4= 0.227


Note that the same 10 standards are run in each case, its only the number
I choose to use in the best fit that is varying. As you can see,
hopefully, the results vary significantly. Any ideas as to why this might
happen? Any advice you can give on attaining more consistent results would
be greatly appreciated.

Thank you!

Skya Fawcett
PhD Candidate
Department of Geological Sciences and Geological Engineering
Queen's University, Kingston, Canada