  Using an eigenspectrum decomposition technique, we separate the host galaxy
from the broad line active galactic nucleus (AGN) in a set of 4666 spectra from
the Sloan Digital Sky Survey (SDSS), from redshifts near zero up to about 0.75.
The decomposition technique uses separate sets of galaxy and quasar
eigenspectra to efficiently and reliably separate the AGN and host
spectroscopic components. The technique accurately reproduces the host galaxy
spectrum, its contributing fraction, and its classification. We show how the
accuracy of the decomposition depends upon S/N, host galaxy fraction, and the
galaxy class. Based on the eigencoefficients, the sample of SDSS broad-line AGN
host galaxies spans a wide range of spectral types, but the distribution
differs significantly from inactive galaxies. In particular, post-starburst
activity appears to be much more common among AGN host galaxies. The
luminosities of the hosts are much higher than expected for normal early-type
galaxies, and their colors become increasingly bluer than early-type galaxies
with increasing host luminosity. Most of the AGNs with detected hosts are
emitting at between 1% and 10% of their estimated Eddington luminosities, but
the sensitivity of the technique usually does not extend to the Eddington
limit. There are mild correlations among the AGN and host galaxy
eigencoefficients, possibly indicating a link between recent star formation and
the onset of AGN activity. The catalog of spectral reconstruction parameters is
available as an electronic table.
