The least-squares goodness-of-fit parameter S for all
reflections included in the refinement after the final cycle
of refinement. Ideally, account should be taken of parameters
restrained in the least-squares refinement. See also
_refine_ls_restrained_S_ definitions.
{ sum | w | Y(obs) - Y(calc) |2 | }1/2
S = { ----------------------------------- }
{ Nref - Nparam }
Y(obs) = the observed coefficients
(see _refine_ls_structure_factor_coef)
Y(calc) = the calculated coefficients
(see _refine_ls_structure_factor_coef)
w = the least-squares reflection weight
[1/(u2)]
u = standard uncertainty
Nref = the number of reflections used in the refinement
Nparam = the number of refined parameters
and the sum is taken over the specified reflections