  Transit and radial velocity models were applied to archival data in order to
examine exoplanet properties, in particular for the recently discovered
super-Earth GJ 357b. There is however considerable variation in estimated model
parameters across the literature, and especially their uncertainty estimates.
This applies even for relatively uncomplicated systems and basic parameters.
Some published accuracy values thus appear highly over-optimistic. We present
our reanalyses with these variations in mind and specify parameters with
appropriate confidence intervals for the exoplanets Kepler-1b, -2b, -8b, -12b,
-13b, -14b, -15b, -40b \& -77b and 51 Peg. More sophisticated models in
WinFitter, EXOFAST, and DACE were applied, leading to mean planet densities for
Kepler-12b, -14b, -15b, and -40b as: $0.11 \pm 0.01$, $4.04 \pm 0.58$, $0.43
\pm 0.05$, and $1.19^{+0.31}_{-0.36}$ g per cc respectively. We confirm a rocky
mean density for the Earth-like GJ357b, although we urge caution about the
modelling given the low S/N data. We cannot confidently specify parameters for
the other two proposed planets in this system.
