I have an addition to Shelly's "practical" advice: 2e) Try the fit at different k-weights. (If you were fitting at multiple k-weight simultaneously, try one k-weight at a time.) In my experience, with a reasonable k-range you may find the statistical quality of your fit (r-factor, chi-square) changes markedly, but the fitted parameters should not drift outside of the ranges defined by their uncertainties. If they do, it is either a sign that you should reduce the k-range or that you have a tenuous and unstable fit that should be viewed with considerable skepticism. --Scott Calvin Sarah Lawrence College At 04:03 PM 4/27/2004 -0500, you wrote:
2) Pull your data into Artemis. Use the good k-range that you determined from step one. 2b) Determine a model that works and look at the results including the uncertainties. 2c) Increase the k-range and compare the results. Try to decrease kmin and increase kmax. Do one thing at a time and see how the results vary. You will need to make a lot of comparisons, see how your results and uncertainties change as you adjust these values. 2d) Decide on a k-range that gives you the "best" results.
Shelly