# Changes

,  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:
$+ R_{scale}=\frac{\sum_{hkl}\vert F_{hkl,i}-F_{hkl,j}\vert}{0.5\sum_{hkl} F_{hkl,i}+F_{hkl,j}} +$
+
: $+ R_{scale}=\frac{\sum_{hkl}\vert F_{hkl,i}-F_{hkl,j}\vert}{0.5\sum_{hkl} F_{hkl,i}+F_{hkl,j}} +$
+

+

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
$+ R=\frac{\sum_{hkl}\vert F_{hkl}^{obs}-F_{hkl}^{calc}\vert}{\sum_{hkl} F_{hkl}^{obs}} +$
+
: $+ R=\frac{\sum_{hkl}\vert F_{hkl}^{obs}-F_{hkl}^{calc}\vert}{\sum_{hkl} F_{hkl}^{obs}} +$
+

+

where $F_{hkl}^{obs}$ and $F_{hkl}^{calc}$ 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 $F_{hkl}^{obs}$ and $F_{hkl}^{calc}$ 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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