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== 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_{merge} = \frac{\sum_{hkl}\vert I_{hkl}-\langle I_{hkl}\rangle\vert}{\sum_{hkl}I_{hkl}}
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R = \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)}}
   
</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
1,313

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