  We investigate the relationship between X-ray and optical line emission in
340 nearby AGN selected above 10 keV using Swift BAT. We find a weak
correlation between the extinction corrected [O III] and hard X-ray luminosity
(14-195 keV) with a [OIII] large scatter (R_Pear = 0.64, sigma = 0.62 dex) and
a similarly large scatter with the intrinsic 2-10 keV to [O III] luminosities
(RPear=0.63, sigma = 0.63 dex). Correlations of the hard X-ray fluxes with the
fluxes of high-ionization narrow lines ([O III], He II, [Ne III] and [Ne V])
are not significantly better than with the low ionization lines (Halpha,
[SII]). Factors like obscuration or physical slit size are not found to be a
significant part of the large scatter. In contrast, the optical emission lines
show much better correlations with each other (sigma = 0.3 dex) than with the
X-ray flux. The inherent large scatter questions the common usage of narrow
emission lines as AGN bolometric luminosity indicators and suggests that other
issues such as geometrical differences in the scattering of the ionized gas or
long term AGN variability are important.
