  We present a statistical assessment of both, observed and reported,
photometric uncertainties in the OGLE-IV Galactic bulge microlensing survey
data. This dataset is widely used for the detection of variable stars,
transient objects, discovery of microlensing events, and characterization of
the exo-planetary systems. Large collections of RR Lyrae stars and Cepheids
discovered by the OGLE project toward the Galactic bulge provide light curves
based on this dataset. We describe the method of analysis, and provide the
procedure, which can be used to update preliminary photometric uncertainties,
provided with the light curves, to the ones reflecting the actual observed
scatter at a given magnitude and for a given CCD detector of the OGLE-IV
camera.This is of key importance for data modeling, in particular, for the
correct estimation of the goodness of fit.
