  We study hemispherical power asymmetry (Eriksen et. al. 2004, Hansen et. al.
2004, Hansen et. al. 2009) in the WMAP 9-year data. We analyse the combined V-
and W-band sky maps, after application of the KQ85 mask, and find that the
asymmetry is statistically significant at the 3.4sigma confidence level for
ell=2-600, where the data is signal dominated, with a preferred asymmetry
direction (l,b)=(227,-27). Individual asymmetry axes estimated from six
independent multipole ranges are all consistent with this direction.
Subsequently, we estimate cosmological parameters on different parts of the sky
and show that the parameters A_s, n_s and Omega_b are the most sensitive to
this power asymmetry. In particular, for the two opposite hemispheres aligned
with the preferred asymmetry axis, we find n_s = 0.959 \pm 0.022 and n_s =
0.989 \pm 0.024, respectively.
