Dear all, I was looking at a 3 angstrom structure from 2015 with relatively bad statistics, so I decided to look at the pdb-redo of said structure. Surprisingly, pdb-redo statistics are even worse. As you can see on the attached picture, the pdb-redo Rfree comes with a caveat:
R-free was considered biased, the estimated unbiased R-free was used I understand that the R-free was considered biased because a new (Rfree) test set was determined. However, I'm not sure what is the unbiased R-free is / how it is calculated in this case? Thanks in advance, Best, Nadia