Dear all, How to obtain correlation matrix (using GSAS)? Is there any option with EXPGUI?
regards, Santosh Babu On Tue, Apr 8, 2008 at 8:33 PM, Brian H. Toby <[EMAIL PROTECTED]> wrote: > The sign of the numbers indicates correlation vs. anticorrelation. For > example, Uiso's correlate between atom 1 and 2 in phase "1 1 1UISO" & > "1 2UISO" so that Uiso increasing on one atom has a similar impact as an > increase on the other. In the case of the reciprocal cell tensor (related to > cell parameters) an increase on one of the diagonal terms has a similar > effect as a decrease on the zero correction ("1 RM11" & "ZERO 1"). > > Brian > > > On Apr 8, 2008, at 8:55 AM, Leopoldo Suescun wrote: > > Dear Gerard, > Here is how to read it: > > The correlation matrix terms greater than 0.50 are > 1 1UISO-1 2UISO 5011 3UISO 687 1HSCL 801 > 1 2UISO- 1HSCL 650 > 1 3UISO- 1HSCL 852 > 1 RM11-ZERO 1 -642 > 1 RM22-ZERO 1 -640 > 1 RM33-ZERO 1 -692 > 1ABS1- 1ABS2 1000 > 1 1PF 2-1 1PF 3 -727 > v-cov distribution 0...1 by 0.05 > 430 125 77 34 7 10 7 2 0 1 1 0 2 > 3 1 0 1 1 0 1 > > > 1st column (8 characters wide): Variable 1, 2nd column: (also 8 > characters wide) Variable 2, with "-" separating both columns, 3rd > column (6 characters wide) the correlation value multiplied by 1000. > Following collumns are show if more paramters have correlations greater > than 0.5 with the parameters in the first collumn. So in this case, 4th > collumn (8 characters wide with no separation from 3rd): Variable 2', > 5th collumn (6 char wide): correlation between Var1 and Var2', etc for > var 2''... > > So you can read the first column this way: > 1 1UISO (Iso thermal param. for atom 1 in phase 1) shows a correlation > of 0.501 with 1 2UISO (iso param for atom 2 in phase 1) so thermal > parameters for atoms 1 and 2 inphase one have 50% correlation. > 1 1UISO shows .687 corelation with 1 3UISO, or atom's 1 and 3 Uisos > are correlated 68.7% > 1 1UISO is correlated with histogram scale factor by 80.1 % > > ABS = absorption correction if my memory is good but you can check in > the GSAS manual that accompanies GSAS distribution. You have a problem > with the setup of the refinement because you have 2 absorption > corrections and both parameters are correlated by 100% so they are not > refining independently. I don't remember what the numbers before and > after ABS mean (histogram, phase, model applied) but check in the manual > and you'll find it. > > The last line, v-cov distribution 0...1 by 0.05 shows the values in a > histogram with range of covariances from 0 to 1 divided in classes 0.05 > wide. First value means that 430 pairs of parameters show absolute value > of correlation between 0.0 and 0.025, 2nd value means 127 parameters > show absolute value of correlation between 0.025 and 0.075 and so forth. > > The top list only gives those higher than 0.5 in absolute value so you > expect 10 counting the last 10 entries in the bottom line, as shown. > > Hope this helps. > Leo > > Dr. Leopoldo Suescun > Argonne National Laboratory > Materials Science Division Bldg 223 > 9700 S. Cass Ave. Argonne IL 60439 > Phone: 1 (630) 252-9760 > Fax: 1 (630) 252-7777 > > ----- Original Message ----- > From: "Gerard, Garcia S" <[EMAIL PROTECTED]> > Date: Tuesday, April 8, 2008 7:37 am > Subject: correlation matrix interpretation > > Dear all, > > Could you please help me to translate this chunk of the correlation > matrix?HSCL is the histogram scale factor > PF profile coefficients > RMii lattice parameters > ABS? > UISo thermal parameters > > how do i interpret the numbers? and the signs? how strongly > correlated these variables are? > > regards > > > > > -- > Heriot-Watt University is a Scottish charity > registered under charity number SC000278. > > > <leopoldo.vcf> > > > ******************************************************************** Brian > H. Toby, Ph.D. office: 630-252-5488 > Materials Characterization Group Leader, Advanced Photon Source > 9700 S. Cass Ave, Bldg. 433/D003 work cell: 630-327-8426 > Argonne National Laboratory secretary (Marija): 630-252-5453 > Argonne, IL 60439-4856 e-mail: brian dot toby at anl dot gov > ******************************************************************** > > >