Sample variance and Lyman-alpha forest transmission statistics
  We compare the observed probability distribution function of the transmission
in the \HI\ Lyman-alpha forest, measured from the UVES 'Large Programme' sample
at redshifts z=[2,2.5,3], to results from the GIMIC cosmological simulations.
Our measured values for the mean transmission and its PDF are in good agreement
with published results. Errors on statistics measured from high-resolution data
are typically estimated using bootstrap or jack-knife resampling techniques
after splitting the spectra into chunks. We demonstrate that these methods tend
to underestimate the sample variance unless the chunk size is much larger than
is commonly the case. We therefore estimate the sample variance from the
simulations. We conclude that observed and simulated transmission statistics
are in good agreement, in particular, we do not require the temperature-density
relation to be 'inverted'.
