  The equation of state of the quark gluon plasma is a key ingredient of heavy
ion phenomenology. In addition to the traditional Taylor method, several novel
approximation schemes have been proposed with the aim of calculating it at
finite baryon density. In order to gain a pragmatic understanding of the limits
of these schemes, we compare them to direct results at $\mu_B>0$, using
reweighting techniques free from an overlap problem. We use 2stout improved
staggered fermions with 8 time-slices and cover the entire RHIC BES range in
the baryochemical potential, up to $\mu_B/T=3$.
