  We present the analysis performed on spectropolarimetric data of 97 O-type
targets included in the framework of the MiMeS (Magnetism in Massive Stars)
Survey. Mean Least-Squares Deconvolved Stokes I and V line profiles were
extracted for each observation, from which we measured the radial velocity,
rotational and non-rotational broadening velocities, and longitudinal magnetic
field. The investigation of the Stokes I profiles led to the discovery of 2 new
multi-line spectroscopic systems (HD46106, HD204827) and confirmed the presence
of a suspected companion in HD37041. We present a modified strategy of the
Least-Squares Deconvolution technique aimed at optimising the detection of
magnetic signatures while minimising the detection of spurious signatures in
Stokes V. Using this analysis, we confirm the detection of a magnetic field in
6 targets previously reported as magnetic by the MiMeS collaboration (HD108,
HD47129A2, HD57682, HD148937, CPD-28 2561, and NGC 1624-2), as well as report
the presence of signal in Stokes V in 3 new magnetic candidates (HD36486,
HD162978, HD199579). Overall, we find a magnetic incidence rate of 7+/-3%, for
108 individual O stars (including all O-type components part of multi-line
systems), with a median uncertainty of the longitudinal field measurements of
about 50\,G. An inspection of the data reveals no obvious biases affecting the
incidence rate or the preference for detecting magnetic signatures in the
magnetic stars. Similar to A- and B-type stars, we find no link between the
stars' physical properties (e.g. Teff, mass, age) and the presence of a
magnetic field. However, the Of?p stars represent a distinct class of magnetic
O-type stars.
