  In this thesis, the field star Initial Mass Function (IMF) and chemical
evolution parameters for the Milky Way (MW) are derived using a forward
modelling technique in combination with Bayesian statistics. Starting from a
local MM disc model, observations of stellar samples in the Solar Neighbourhood
are synthesised and compared to the corresponding volume-complete observational
samples of Hipparcos stars. The resulting IMF, derived from observations in the
range from 0.5 to 8Msun, is a two-slope broken power law with powers of -1.49
+- 0.08 and -3.02 +- 0.06 for the low-mass slope and the high-mass slope,
respectively, with a break at 1.39 +- 0.05Msun. In order to constrain the IMF
for stars more massive than 8Msun, a fast and flexible chemical enrichment
code, Chempy, was developed, which is also able to reproduce spatial and
stellar population selections of observational samples. The inferred high-mass
slope for stellar masses above 6Msun is -2.28 +- 0.09, accounting for the
systematic effects of different yield sets from the literature. This shows that
constraints from chemical modelling, similarly to hydrodynamical simulations of
the Galaxy, demand a Salpeter high-mass index. This is hard to recover from
star count analysis given the rareness of high-mass stars.
