# Core CIF Dictionary version 2.3

# _refine_ls_R_factor_obs

### Name

`'_refine_ls_R_factor_obs'`
**Category:** refine

**Data type:** numb

**Related item:** `'_refine_ls_R_factor_gt'`

**Related function:** replace

**Enumeration range:** 0.0 -> infinity

### Definition

Residual factor for the reflections classified as 'observed'
(see _reflns_observed_criterion) and included in the
refinement. The reflections also satisfy the resolution limits
established by _refine_ls_d_res_high and
_refine_ls_d_res_low. This is the conventional R
factor. See also _refine_ls_wR_factor_ definitions.
sum | F(obs) - F(calc) |
R = ------------------------
sum | F(obs) |
F(obs) = the observed structure-factor amplitudes
F(calc) = the calculated structure-factor amplitudes
and the sum is taken over the specified reflections

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