R factors in Rietveld analysis: How good is good enough?

The definitions for important Rietveld error indices are defined and discussed. It is shown that while smaller error index values indicate a better fit of a model to the data, wrong models with poor quality data may exhibit smaller values error index values than some superb models with very high quality data.

• UD
  U.S. Department of Energy
• OO
  Office of Science