**Definition:**

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 R~B~ or R~Bragg~ 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.

**Type:** float

**Mandatory item:** no

The permitted range is [0.0, infinity)

**Category:** refine_ls_class

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