  The effects of the hadronisation of partons on the distribution of event
shape observables are associated with corrections which are suppressed by
reciprocal powers of the energy scale of the process. The correction is
determined by one non-calculable parameter \alpha_0 for which an universal
value of 0.5 +/- 20% is found from the investigation of the distribution of
event shape observables and their mean values measured in e^+e^- annihilation.
