  The large number of stars for which uninterrupted high-precision photometric
timeseries data are being collected with \textit{Kepler} and CoRoT initiated
the development of automated methods to analyse the stochastically excited
oscillations in main-sequence, subgiant and red-giant stars. Aims: We
investigate the differences in results for global oscillation parameters of G
and K red-giant stars due to different methods and definitions. We also
investigate uncertainties originating from the stochastic nature of the
oscillations. Methods: For this investigation we use Kepler data obtained
during the first four months of operation. These data have been analysed by
different groups using already published methods and the results are compared.
We also performed simulations to investigate the uncertainty on the resulting
parameters due to different realizations of the stochastic signal. Results: We
obtain results for the frequency of maximum oscillation power (nu_max) and the
mean large separation (<delta nu>) from different methods for over one thousand
red-giant stars. The results for these parameters agree within a few percent
and seem therefore robust to the different analysis methods and definitions
used here. The uncertainties for nu_max and <delta nu> due to differences in
realization noise are not negligible and should be taken into account when
using these results for stellar modelling.
