On the use of the merging R factor as a quality indicator for X-ray data

By comparison of the accuracy and the merging R factor (R_merge) of artificially created X-ray data sets, it is demonstrated that R_merge is a poor predictor for the precision of X-ray data. The more often a given reflection is observed, the more precise the average intensity is, whereas R_merge has a tendency to be higher at higher data redundancy.