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~~R_{merge} ~~= \frac{\sum_{hkl}\vert I_{hkl}-\langle I_{hkl}\rangle\vert}{\sum_{hkl}I_{hkl~~}}~~+~~</math>~~
−~~<br/>~~
−~~<br/>~~
−~~<math>~~
−~~R=\frac{\sum_{hkl_{unique}}\vert F_{hkl}^{(obs)}-F_{hkl}^{(calc)}\vert}{\sum_{hkl_{unique}} F_{hkl}^{(obs)~~}}
+

== Definitions ==

== Definitions ==

=== Data quality indicators ===

=== Data quality indicators ===

−* R<sub>sym</sub> and R<sub>merge</sub> : the formula is

+* R<sub>sym</sub> and R<sub>merge</sub> : the formula for both is

<math>

<math>

−R = \frac{\sum_{hkl}\vert I_{hkl}-\langle I_{hkl}\rangle\vert}{\sum_{hkl}I_{hkl}}

−</math>

</math>

+<br>

+<br>

+where <math>\langle I_{hkl}\rangle</math> is the average of symmetry- (or Friedel-) related observations of a unique reflection, and the summation is over all observations, leaving out those that have no symmetry mates (or Friedel) in the dataset.

* Redundancy-independant version of the above: R<sub>meas</sub>

* Redundancy-independant version of the above: R<sub>meas</sub>

* measuring quality of averaged intensities/amplitudes: R<sub>p.i.m.</sub> and R<sub>mrgd-F</sub>

* measuring quality of averaged intensities/amplitudes: R<sub>p.i.m.</sub> and R<sub>mrgd-F</sub>

=== Model quality indicators ===

=== Model quality indicators ===

−* R and R<sub>free</sub> : the formula is (~~LaTex please ~~)

+* R and R<sub>free</sub> : the formula for both is

−<math>

+R=\frac{\sum_{hkl_{unique}}\vert F_{hkl}^{(obs)}-F_{hkl}^{(calc)}\vert}{\sum_{hkl_{unique}} F_{hkl}^{(obs)}}

+</math>

+<br>

+<br>

+where <math>F_{hkl}^{(obs)}</math> and <math>F_{hkl}^{(calc)}</math> have to be scaled w.r.t. each other. R and R<sub>free</sub> differ in the set of reflections they are calculated from: R is calculated for the [[working set]], whereas R<sub>free</sub> is calculated for the [[test set]].

== what do R-factors try to measure, and how to interpret their values? ==

== what do R-factors try to measure, and how to interpret their values? ==

* relative deviation of

* relative deviation of

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