[Ifeffit] ???

Hello, Questions from a beginner in EXAFS...using Athena and Arthemis

From where to get the error bars for number of neighbours, distance and sigsqr (ss)?

What are Chi-square,Reduced Chi-square and R-factor and how should be their values in a fit? Sometimes it happen that "R-factor for this data set" does not have the same value as the first R-factor from results. Why? many thanks, Elena