Comment on "Constraining the smoothness parameter and dark energy using
  observational H(z) data"
  In this Comment we discuss a recent analysis by Yu et al. [RAA 11, 125
(2011)] about constraints on the smoothness $\alpha$ parameter and dark energy
models using observational $H(z)$ data. It is argued here that their procedure
is conceptually inconsistent with the basic assumptions underlying the adopted
Dyer-Roeder approach. In order to properly quantify the influence of the $H(z)$
data on the smoothness $\alpha$ parameter, a $\chi^2$-test involving a sample
of SNe Ia and $H(z)$ data in the context of a flat $\Lambda$CDM model is
reanalyzed. This result is confronted with an earlier approach discussed by
Santos et al. (2008) without $H(z)$ data. In the ($\Omega_m, \alpha$) plane, it
is found that such parameters are now restricted on the intervals $0.66 \leq
\alpha \leq 1.0$ and $0.27 \leq \Omega_m \leq 0.37$ within 95.4% confidence
level (2$\sigma$), and, therefore, fully compatible with the homogeneous case.
The basic conclusion is that a joint analysis involving $H(z)$ data can
indirectly improve our knowledge about the influence of the inhomogeneities.
However, this happens only because the $H(z)$ data provide tighter constraints
on the matter density parameter $\Omega_m$.
