# Core CIF Dictionary version 2.3

# _reflns_shell_Rmerge_F_obs

### Name

`'_reflns_shell_Rmerge_F_obs'`
**Category:** reflns_shell

**Data type:** numb

**Related item:** `'_reflns_shell_Rmerge_F_gt'`

**Related function:** replace

**Must** appear in a looped list

**Enumeration range:** 0.0 -> infinity

### Definition

The value of Rmerge(F) for reflections classified as 'observed'
(see _reflns_observed_criterion) in a given shell.
sum~i~ ( sum~j~ | F~j~ - | )
Rmerge(F) = --------------------------------
sum~i~ ( sum~j~ )
F~j~ = the amplitude of the jth observation of reflection i
= the mean of the amplitudes of all observations of
reflection i
sum~i~ is taken over all reflections
sum~j~ is taken over all observations of each reflection.

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