  Taylor expansion of the thermodynamic potential in powers of the
(baryo)chemical potential $\mu_B$ is a well-known method to bypass the Sign
Problem of Lattice QCD. Due to the difficulty in calculating the higher order
Taylor coefficients, various alternative expansion schemes as well as
resummation techniques have been suggested to extend the Taylor series to
larger values of $\mu_B$. Recently, a way to resum the contribution of the
first $N$ charge density correlation functions $D_1,\dots,D_N$ to the Taylor
series to all orders in $\mu_B$ was proposed in Phys. Rev. Lett. 128, 2, 022001
(2022). The resummation takes the form of an exponential factor. Since the
correlation functions are calculated stochastically, the exponential factor
contains a bias which can be significant for large $N$ and $\mu_B$. In this
paper, we present a new method to calculate the QCD equation of state based on
the well-known cumulant expansion from statistics. By truncating the expansion
at a maximum order $M$, we end up with only finite products of the correlation
functions which can be evaluated in an unbiased manner. Although our formalism
is also applicable for $\mu_B\ne0$, here we present it for the simpler case of
a finite isospin chemical potential $\mu_I$ for which there is no Sign Problem.
We present and compare results for the pressure and the isospin density
obtained using Taylor expansion, exponential resummation and cumulant
expansion, and provide evidence that the absence of bias in the latter actually
improves the convergence.
