Residual factor R for reflections that satisfy the resolution
limits established by _refine.ls_d_res_high and
_refine.ls_d_res_low and the observation limit established by
_reflns.observed_criterion, and that were used as the working
reflections (i.e. were included in the refinement) when the
refinement included the calculation of a 'free' R factor.
Details of how reflections were assigned to the working and
test sets are given in _reflns.R_free_details.
_refine.ls_R_factor_obs should not be confused with
_refine.ls_R_factor_R_work; the former reports the results of a
refinement in which all observed reflections were used, the
latter a refinement in which a subset of the observed
reflections were excluded from refinement for the calculation
of a 'free' R factor. However, it would be meaningful to quote
both values if a 'free' R factor were calculated for most of
the refinement, but all of the observed reflections were used
in the final rounds of refinement; such a protocol should be
explained in _refine.details.
sum|Fobs - Fcalc|
R = ---------------------
Fobs = the observed structure-factor amplitudes
Fcalc = the calculated structure-factor amplitudes
sum is taken over the specified reflections