  We present preliminary results of a 2+1-flavor study of finite-volume effects
in the lattice QCD computation of the leading-order hadronic contribution to
the muon anomalous magnetic moment. We also present methods for obtaining
directly the invariant hadronic polarization function, $\Pi(Q^2)$, and the
Adler function at all discrete lattice values of $Q^2$, including $Q^2=0$.
Results are obtained with HEX-smeared clover fermions.
