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6 bytes added ,  14:05, 26 January 2018
Line 67: Line 67:  
=== Comparing two sets of structure factor amplitudes or intensities ===
 
=== Comparing two sets of structure factor amplitudes or intensities ===
 
The following is symmetric, and suitable for comparing two data sets, or two model amplitudes:
 
The following is symmetric, and suitable for comparing two data sets, or two model amplitudes:
<math>
+
 
R_{scale}=\frac{\sum_{hkl}\vert F_{hkl,i}-F_{hkl,j}\vert}{0.5\sum_{hkl} F_{hkl,i}+F_{hkl,j}}
+
 
</math>
+
: <math>
 +
R_{scale}=\frac{\sum_{hkl}\vert F_{hkl,i}-F_{hkl,j}\vert}{0.5\sum_{hkl} F_{hkl,i}+F_{hkl,j}}
 +
</math>
 +
 
 +
 
 
for amplitudes, and analogously for intensities.
 
for amplitudes, and analogously for intensities.
    
=== Model quality indicators ===
 
=== Model quality indicators ===
 
* R and [[iucr:Free_R_factor|R<sub>free</sub>]] : the formula for both is  
 
* R and [[iucr:Free_R_factor|R<sub>free</sub>]] : the formula for both is  
<math>
+
 
R=\frac{\sum_{hkl}\vert F_{hkl}^{obs}-F_{hkl}^{calc}\vert}{\sum_{hkl} F_{hkl}^{obs}}
+
 
</math>
+
: <math>
 +
R=\frac{\sum_{hkl}\vert F_{hkl}^{obs}-F_{hkl}^{calc}\vert}{\sum_{hkl} F_{hkl}^{obs}}
 +
</math>
 +
 
 +
 
 
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]].
 
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]].
  
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