CORRECT.LP: Difference between revisions
m →Statistics of unique reflections: Rpim calculation |
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== Scaling information == | == Scaling information == | ||
<pre> | <pre> | ||
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DETECTOR_SURFACE_POSITION= 3231 1592 | DETECTOR_SURFACE_POSITION= 3231 1592 | ||
NUMBER OF REFLECTIONS USED FOR DETERMINING CORRECTION FACTORS 4832 | NUMBER OF REFLECTIONS USED FOR DETERMINING CORRECTION FACTORS 4832 | ||
</pre> | |||
=== Details about the error model === | |||
<pre> | |||
****************************************************************************** | |||
CORRECTION PARAMETERS FOR THE STANDARD ERROR OF REFLECTION INTENSITIES | |||
****************************************************************************** | |||
The variance v0(I) of the intensity I obtained from counting statistics is | |||
replaced by v(I)=a*(v0(I)+b*I^2). The model parameters a, b are chosen to | |||
minimize the discrepancies between v(I) and the variance estimated from | |||
sample statistics of symmetry related reflections. This model implicates | |||
an asymptotic limit ISa=1/SQRT(a*b) for the highest I/Sigma(I) that the | |||
experimental setup can produce (Diederichs (2010) Acta Cryst D66, 733-740). | |||
a b ISa | |||
1.042E+00 2.177E-04 66.41 | |||
</pre> | </pre> | ||
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The file XDS_ASCII.HKL actually has all 531700 reflections. | The file XDS_ASCII.HKL actually has all 531700 reflections. | ||
=== Notes === | |||
How to calculate Rpim from the numbers in the table: take the Rmeas value and divide by the square root of the multiplicity. The multiplicity is the number of observations divided by the number of unique reflections. Example: the table above shows Rmeas of 33.5% overall, observed 515976 overall, with 173389 uniques. Thus Rpim = 33.5% / SQRT(515976/173389) = 19.4% . | |||