Weighted residual factor wR for reflections that satisfy the
resolution limits established by _refine_ls_shell.d_res_high
and _refine_ls_shell.d_res_low and the observation limit
established by _reflns.observed_criterion, and that were used
as the test reflections (i.e. were excluded from 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.
( sum|w |Yobs - Ycalc|2| )1/2
wR = ( ---------------------------- )
( sum|w Yobs2| )
Yobs = the observed amplitude specified by
Ycalc = the calculated amplitude specified by
w = the least-squares weight
sum is taken over the specified reflections