  The KATRIN (KArlsruhe TRItium Neutrino) experiment will be analyzing the
tritium beta-spectrum to determine the mass of the neutrino with a sensitivity
of 0.2 eV (90% C.L.). This approach to a measurement of the absolute value of
the neutrino mass relies only on the principle of energy conservation and can
in some sense be called model-independent as compared to cosmology and
neutrino-less double beta decay. However by model independent we only mean in
case of the minimal extension of the standard model. One should therefore also
analyse the data for non-standard couplings to e.g. righthanded or sterile
neutrinos. As an alternative to the frequentist minimization methods used in
the analysis of the earlier experiments in Mainz and Troitsk we have been
investigating Markov Chain Monte Carlo (MCMC) methods which are very well
suited for probing multi-parameter spaces. We found that implementing the
KATRIN chi squared function in the COSMOMC package - an MCMC code using
Bayesian parameter inference - solved the task at hand very nicely.
