On the use of galaxies as clocks and the universal expansion
  We set out to rederive the 8 Hubble parameter values obtained from estimated
relative galaxy ages in Simon et al, PRD 71 (2005). We find that to obtain the
level of precision claimed in $H(z)$, unrealistically small galaxy age
uncertainties have to be assumed. Also, some parameter values will be
correlated. In our analysis we find that the uncertainties in the Hubble
parameter values are significantly larger when 8 independent $H(z)$ are
obtained using Monte Carlo sampling. Smaller uncertainties can be obtained
using Gaussian processes, but at the cost of strongly correlated results. We do
not obtain any useful constraints on the Hubble parameter from the galaxy data
employed.
