  The gravitational-wave candidate GW151216 is a proposed binary black hole
event from the first observing run of the Advanced LIGO detectors. Not
identified as a bona fide signal by the LIGO--Virgo collaboration, there is
disagreement as to its authenticity, which is quantified by $p_\text{astro}$,
the probability that the event is astrophysical in origin. Previous estimates
of $p_\text{astro}$ from different groups range from 0.18 to 0.71, making it
unclear whether this event should be included in population analyses, which
typically require $p_\text{astro}>0.5$. Whether GW151216 is an astrophysical
signal or not has implications for the population properties of stellar-mass
black holes and hence the evolution of massive stars. Using the astrophysical
odds, a Bayesian method which uses the signal coherence between detectors and a
parameterised model of non-astrophysical detector noise, we find that
$p_\text{astro}=0.03$, suggesting that GW151216 is unlikely to be a genuine
signal. We also analyse GW150914 (the first gravitational-wave detection) and
GW151012 (initially considered to be an ambiguous detection) and find
$p_\text{astro}$ values of 1 and 0.997 respectively. We argue that the
astrophysical odds presented here improve upon traditional methods for
distinguishing signals from noise.
