  Since there is now a growing wish by referees to judge the underpinning data
for a submitted article it is timely to provide a summary of the data
evaluation checks required to be done by a referee. As these checks will vary
from field to field this article focuses on the needs of biological X-ray
crystallography articles, which is the predominantly used method leading to
depositions in the PDB. The expected referee checks of data underpinning an
article are described with examples. These checks necessarily include that a
referee checks the PDB validation report for each crystal structure
accompanying the article submission; this check whilst necessary is not
sufficient for a complete evaluation. A referee would be expected to undertake
one cycle of model refinement of the authors biological macromolecule
coordinates against the authors processed diffraction data and look at the
various validation checks of the model and Fo-Fc electron density maps in e.g.
Phenix_refine and in COOT. If the referee deems necessary the diffraction data
images should be reprocessed (e.g. to a different diffraction resolution than
the authors submission). This can be requested to be done by the authors or if
the referee prefers can be undertaken directly by the referee themselves. A
referee wishing to do these data checks may wish to receive a certificate that
they have command of these data science skills. The organisation of such
voluntary certification training can e.g. be via those crystallography
associations duly recognised by the IUCr to issue such certificates.
