  We apply a data-driven method to STAR Au+Au collisions at $\sqrt{s_{NN}}=200$
GeV to isolate $\Delta\eta$-dependent and $\Delta\eta$-independent correlations
by using two- and four-particle Q-cumulant $v_{n}$ measurements. The
$\Delta\eta$-independent part, dominated by flow, is found to be
$\eta$-independent within the STAR TPC of $\pm1$ unit of pseudo-rapidity. The
$\Delta\eta$-dependent part may be associated to nonflow, and is responsible
for the $\Delta\eta$ drop in the measured two-particle $v_{2}$ cumulant. We
combine our result to four- and six-particle cumulants to gain further insights
on the nature of flow fluctuations.
