  We aim to demonstrate the efficiency of a Bayesian approach in analysing
radial velocity data by reanalysing a set of radial velocity measurements. We
present Bayesian analysis of a recently published set of radial velocity
measurements known to contain the signal of one extrasolar planetary candidate,
namely, HD 11506. The analysis is conducted using the Markov chain Monte Carlo
method and the resulting distributions of orbital parameters are tested by
performing direct integration of randomly selected samples with the
Bulirsch-Stoer method. The magnitude of the stellar radial velocity
variability, known as jitter, is treated as a free parameter with no
assumptions about its magnitude. We show that the orbital parameters of the
planet known to be present in the data correspond to a different solution when
the jitter is allowed to be a free parameter. We also show evidence of an
additional candidate, a 0.8 MJup planet with period of about 0.5 yr in orbit
around HD 11506. This second planet is inferred to be present with a high level
of confidence.
