Hi List, Here's my most recent data. I was able to look at the individual paths and changed my R-range to 2-4.5 angstroms on the first set of data, I set the second set of data to the same range, although 4 works better as a maximum for that set. The k-range on the second range had to be truncated though. Six paths are used for each fit, same parameters, except for amp (0.7 for one ~0.8 for the other). The seperate data sets still have a few parameters that are outside of the error bars of the other (ss2,ss3,ss4,alpha, alpha2,alpha5). What can I do to get these beamlines to agree? delr_# define alpha# * reff all other parameters guessed. ss for each path, only one e0 for all Thanks for the help, Dan First Data set -- Full k-range works best, Full range used for fit. Project title : Fitting merge 10_15_04.chi Guess parameters +/- uncertainties (initial guess): e0 = 0.8686930 +/- 1.1038290 (guessed as 0.868694 (1.103841)) ss = 0.0041150 +/- 0.0004990 (guessed as 0.004115 (0.000499)) ss2 = 0.0044360 +/- 0.0004450 (guessed as 0.004436 (0.000445)) ss3 = 0.0243560 +/- 0.0201400 (guessed as 0.024368 (0.020159)) ss4 = -0.0065470 +/- 0.0047820 (guessed as -0.006545 (0.004786)) ss5 = -0.0016100 +/- 0.0050490 (guessed as -0.001611 (0.005047)) ss6 = 0.0059980 +/- 0.0139390 (guessed as 0.005996 (0.013935)) alpha = -0.0011360 +/- 0.0029380 (guessed as -0.001136 (0.002938)) alpha2 = 0.0071480 +/- 0.0019780 (guessed as 0.007148 (0.001978)) alpha3 = -0.0060900 +/- 0.0273580 (guessed as -0.006078 (0.027378)) alpha4 = -0.0198570 +/- 0.0154200 (guessed as -0.019851 (0.015430)) alpha5 = 0.1399050 +/- 0.0148530 (guessed as 0.139906 (0.014848)) alpha6 = 0.0199630 +/- 0.0268690 (guessed as 0.019961 (0.026862)) Def parameters: delr_1 = -0.0051820 delr_2 = 0.0326180 delr_3 = -0.0277930 delr_4 = -0.0906110 delr_5 = 0.6384270 delr_6 = 0.0910950 Set parameters: amp1 = .7 Correlations between variables: e0 and alpha --> 0.8170 e0 and alpha2 --> 0.6726 ss and ss2 --> 0.6591 alpha and alpha2 --> 0.5516 alpha5 and alpha6 --> -0.4856 e0 and alpha3 --> 0.4083 alpha3 and alpha4 --> 0.3588 ss5 and ss6 --> -0.3581 alpha and alpha3 --> 0.3100 alpha2 and alpha3 --> 0.3045 ss2 and alpha6 --> 0.2745 e0 and ss3 --> 0.2649 ss and ss3 --> 0.2627 ss2 and ss3 --> 0.2626 ss6 and alpha5 --> -0.2510 All other correlations are below 0.25 Second Data Set -- Trucated k-range (2-13.5) Project title : Fitting merge 10_15_04.chi Independent points = 25.270507813 Number of variables = 14.000000000 Chi-square = 1202.598221935 Reduced Chi-square = 106.703108852 R-factor = 0.057229121 Measurement uncertainty (k) = 0.000827712 Measurement uncertainty (R) = 0.022111003 Number of data sets = 1.000000000 Guess parameters +/- uncertainties (initial guess): amp = 0.7976070 +/- 0.1361170 (guessed as 0.776348 (0.139898)) ss = 0.0037770 +/- 0.0015530 (guessed as 0.003589 (0.001617)) e0 = 0.5608430 +/- 1.8018380 (guessed as 0.642687 (1.861307)) alpha = -0.0061290 +/- 0.0049080 (guessed as -0.005966 (0.005078)) ss2 = 0.0029050 +/- 0.0009970 (guessed as 0.002686 (0.001078)) ss3 = 0.0075410 +/- 0.0094220 (guessed as 0.005992 (0.008858)) ss4 = -0.0110250 +/- 0.0035850 (guessed as -0.011776 (0.004653)) ss5 = -0.0042000 +/- 0.0078070 (guessed as -0.007610 (0.005250)) alpha2 = 0.0038110 +/- 0.0030450 (guessed as 0.003762 (0.003187)) alpha3 = -0.0037820 +/- 0.0145580 (guessed as 0.001200 (0.015976)) alpha4 = -0.0212550 +/- 0.0107080 (guessed as -0.011852 (0.014417)) alpha5 = 0.1151980 +/- 0.0236640 (guessed as 0.113430 (0.014973)) ss6 = 0.0028560 +/- 0.0166050 (guessed as -0.007250 (0.003624)) alpha6 = 0.0193530 +/- 0.0299640 (guessed as 0.001791 (0.008195)) Def parameters: delr_1 = -0.0279670 delr_2 = 0.0173920 delr_3 = -0.0172570 delr_4 = -0.0969910 delr_5 = 0.5256830 delr_6 = 0.0883130 Correlations between variables: amp and ss --> 0.8382 e0 and alpha --> 0.8048 amp and ss2 --> 0.7964 e0 and alpha2 --> 0.7533 ss3 and alpha5 --> 0.7397 ss5 and alpha4 --> -0.6999 ss and ss2 --> 0.6591 alpha and alpha2 --> 0.6159 alpha5 and ss6 --> 0.6116 ss5 and alpha3 --> -0.5790 ss5 and alpha6 --> -0.5023 ss3 and ss6 --> 0.4804 alpha4 and alpha5 --> -0.4375 e0 and alpha3 --> 0.4083 ss4 and ss5 --> -0.4047 ss3 and alpha4 --> -0.3972 alpha5 and alpha6 --> 0.3827 alpha3 and alpha6 --> 0.3498 ss3 and ss5 --> -0.3278 amp and ss3 --> 0.3209 ss4 and ss6 --> 0.3181 alpha and alpha3 --> 0.3100 alpha2 and alpha3 --> 0.3045 ss4 and alpha3 --> 0.2948 amp and ss5 --> 0.2820 ss2 and alpha6 --> 0.2745 ss and ss3 --> 0.2627 ss2 and ss3 --> 0.2626 amp and alpha6 --> 0.2589 alpha2 and alpha5 --> 0.2581 All other correlations are below 0.25