Dear Monica, We can also, perhaps, most helpfully quote from our forthcoming article in J Appl Cryst, Volume 48, Part 3 (June 2015):-
"An online computing server, Online_DPI, is created and maintained to calculate the ‘Cruickshank DPI’ value for a given three-dimensional protein or macromolecular structure. Also, it estimates the atomic coordinate error for all the atoms available in the structure. It is an easy-to-use web server that enables the users to visualize the computed values dynamically on the client machine. The users can provide the PDB-identification code or upload the three-dimensional atomic coordinates from the client machine. The computed DPI value for the structure and its atomic coordinate errors for all the atoms are included in the revised PDB file." So you can see directly for any specific atom movement, whether it is significant at e.g. the 3 sigma level. So, you don't need to use the average over all the atoms DPI error value, but the atom you are especially interested in. Best wishes, Guru
