Changes

=== 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_free]] : the formula for both is  

* R and [[iucr:Free_R_factor|R_free]] : 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_free differ in the set of reflections they are calculated from: R is calculated for the [[working set]], whereas R_free 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_free differ in the set of reflections they are calculated from: R is calculated for the [[working set]], whereas R_free is calculated for the [[test set]].