For each reflection class, the residual factor R(I) for the
reflections judged significantly intense (i.e. satisfying the
threshold specified by _reflns.threshold_expression) and
included in the refinement.
This is most often calculated in Rietveld refinements
against powder data, where it is referred to as RB or RBragg.
sum | I(obs) - I(calc) |
R(I) = ------------------------
sum | I(obs) |
I(obs) = the net observed intensities
I(calc) = the net calculated intensities
and the sum is taken over the reflections of this class.