Dear Matt, Thank you very much for your response. One more question. What value of corelation is acceptable/publishable? also having a correlation number means the fit is not finished and I should change the values of variable that are correlated? is that so? Best Pushkar
On Tue, Nov 24, 2015 at 1:48 PM, Matt Newville <[email protected]> wrote: > Pushkar, > > On Mon, Nov 23, 2015 at 8:59 PM, pushkar shejwalkar < > [email protected]> wrote: > >> Dear All, >> I am trying to fit in Pd compound and the fit that I obtained looks >> kinda good. I used Pd metal and Pd(OAc)2 shells for fitting. These >> standards were collected and fitted simultaneously and I got the SO2 value >> there as 0.67 with Pd foil coordination number as 12 which is correct when >> considered Pd foil CN. Next while fitting the actual sample (unknown) I >> used the formula in SO2 column as amp*N1 and put amp as 0.67 and N as 1. I >> kept N1 as variable (Guess). same I did for the second shell of Pd-O with >> N2. amp is kept on SET value of 0.67. After fitting I received the N1 and >> N2 value as 5.6 (0.5) and 1.6 (0.7) (roughly). however, when I checked the >> correlations between the variables I got the values as given in the log >> file attached. I saw there is some correlation between bkg01_01 and N2 and >> many such correlations between bkg values. I have so far never seen such >> correlations. What are the implications of these correlations? does this >> means that my fitting assumptions are incorrect. does correlations values >> in negative indicates something? >> > > Correlation between two variables A and B means that if you changed one > variable (A) away from its best-fit value, you could improve that fit by > changing the other variable (B). In fact the correlation tells you by how > much, and (from the sign) in what direction that change would be. > > A correlation of 0 means that if one changed A, B would not need to change > at all. A correlation of 1 would mean that a change in A by 1 standard > error (the reported error), B would have to change by 1 standard error. > And, again, the sign gives the direction of that change. > > Having correlated values does not mean that your assumptions are incorrect. > > Thank you very much for the input. By the way my RBKG is 1.2 in athena and >> I used this same file for fitting purpose and on artemis I used rmin 1.2 >> and rmax 3.4. All these information are in log file attached >> Any help in understanding this is appreciated. >> >> -- >> Best Regards, >> Pushkar Shejwalkar. >> Post-doctoral -Researcher, >> Tokyo Engineering University, >> Tokyo-to >> Japan >> >> >> _______________________________________________ >> Ifeffit mailing list >> [email protected] >> http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit >> Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit >> >> > > --Matt > > _______________________________________________ > Ifeffit mailing list > [email protected] > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit > Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit > > -- Best Regards, Pushkar Shejwalkar. Post-doctoral -Researcher, Tokyo Engineering University, Tokyo-to Japan
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