The galactocentric radius dependent upper mass limit of young star
  clusters: stochastic star formation ruled out
  It is widely accepted that the distribution function of the masses of young
star clusters is universal and can be purely interpreted as a probability
density distribution function with a constant upper mass limit. As a result of
this picture the masses of the most-massive objects are exclusively determined
by the size of the sample. Here we show, with very high confidence, that the
masses of the most-massive young star clusters in M33 decrease with increasing
galactocentric radius in contradiction to the expectations from a model of a
randomly sampled constant cluster mass function with a constant upper mass
limit. Pure stochastic star formation is thereby ruled out. We use this example
to elucidate how naive analysis of data can lead to unphysical conclusions.
