              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 working (i.e., included in refinement) reflections when\
               refinement included 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 |Y~obs~ - Y~calc~|^2^| )^1/2^\
               wR = ( ---------------------------- )\
                    (        sum|w Y~obs~^2^|      )\
\
               Y~obs~  = the observed amplitude specified by\
                         _refine.ls_structure_factor_coef\
               Y~calc~ = the calculated amplitude specified by\
                         _refine.ls_structure_factor_coef\
               w       = the least squares weight\
\
               sum is taken over the specified reflections