# Core CIF Dictionary version 2.3

# _refine_ls_R_I_factor

### Name

`'_refine_ls_R_I_factor'`
**Category:** refine

**Data type:** numb

**Enumeration range:** 0.0 -> infinity

### Definition

Residual factor R(I) for significantly intense reflections
(satisfying _reflns_threshold_expression) and included in
the refinement.
This is most often calculated in Rietveld refinements of 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 specified reflections

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