Using the<i>t</i>-distribution to improve the absolute structure assignment with likelihood calculations

The previously described method for absolute structure determination [Hooft, Straver &amp; Spek (2008). J. Appl. Cryst. 41 , 96–103] assumes a Gaussian error distribution. The method is now extended to make it robust against poor data with large systematic errors with the introduction of the Student t -distribution. It is shown that this modification makes very little difference for good data but dramatically improves results for data with a non-Gaussian error distribution.