Extending the Eigenvector 1 Space to the Optical Variability of Quasars
  We introduce a new physical parameter, the optical variability amplitude, to
the well-established Eigenvector 1 space of quasars and test a sample of
long-term B-band light curves of 42 PG quasars monitored by Giveon et al.
(1999). We find that the optical variability amplitude strongly correlates with
the intensity ratio of Fe II to H$\beta$, H$\beta$ width and peak luminosity at
5007$\rm{\AA}$. We briefly discuss the physical meaning of our findings and
suggest that the Eddington ratio may be a key factor in determining a quasar's
variability.
