Quality indicators in macromolecular crystallography: definitions and applications

The genesis of this chapter was a perceived need for a single location in the volume, in which consensus definitions could be found for the many statistical indicators of quality or figures of merit that have been developed to monitor a macromolecular crystallography MX experiment and its final outcome, a model. The evolving experiment has generated a rich collection of R values, signal to noise indicators, correlation coefficients and other figures of merit. As improvements in data collection, processing and other aspects of the experiment continue, we can expect a continued evolution of new or improved indicators of quality with which to monitor the impact of those improvements