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bsimpkins1-Visitor
1-Visitor
January 11, 2019
Question

global fit multiple data sets

  • January 11, 2019
  • 7 replies
  • 4580 views

hi all, 

title  (hopefully) says it all.  I have several data sets.  Each one will be fit the to the same fit function and the sets will share some, but not all, of the fit variables.

I have a clumsy attempt at this in the attached sheet (Prime 4.0 along with excel data).  I basically use "minimize" to minimize a standard error expression which has several fit expressions in it (one for each data set).  The problem is that the resulting fit values are nearly identical to the initial guesses!  I've tried reducing the TOL but that doesn't help.

 

cheers,

blake

 

7 replies

W
Werner_E25-Diamond I
25-Diamond I
January 11, 2019

Guess you have a typo in the definition of sse. You wrote A.4 instead of A.1

W
Werner_E25-Diamond I
25-Diamond I
January 11, 2019

Here is an approach without your sse function using minerr and letting Prime do the sse minimization that way. Its better with this approach to set the vectors to 0 and not the sum of its elements.

Are the results more suitable?

B.PNG

 

B
bsimpkins1-VisitorAuthor
1-Visitor
January 11, 2019

thanks.  the "minerr" approach is better.  it gives results that are not locked to original guesses (and is much faster!).  however, the results are quite sensitive to initial guesses.   i'll dig into a different data set.

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