  We estimate the biases caused by the coherent deflection of cosmic rays due
to the Galactic magnetic field (GMF) in maximum-likelihood analysis for
searches of ultrahigh-energy cosmic ray (UHECR) sources in the literature. We
simulate mock event datasets with a set of assumptions for the starburst galaxy
(SBG) source model (arXiv:1801.06160), coherent deflection by a GMF model
(arXiv:1204.3662,arXiv:1210.7820), and mixed-mass composition
(arXiv:1901.03338); we then conduct a maximum-likelihood analysis without
accounting for the GMF in the same manner as previous studies. We find that the
anisotropic fraction $f_{\rm ani}$ is estimated systematically lower than the
true value. We estimate the true parameters which are compatible with the
best-fit parameters reported in (arXiv:1801.06160), and find that except for a
narrow region with a large anisotropic fraction and small separation angular
scale a wide parameter space is still compatible with the experimental results.
We also develop a maximum-likelihood method that takes into account the GMF
model and confirm in the MC simulations that we can estimate the true
parameters within a 1$\sigma$ contour under the ideal condition that we know
the event-by-event mass and the GMF.
