The widths of the bands are generally much larger than the statistical uncertainties. In a few cases, the Monte Carlo prediction obtained by one of the Collaborations differs significantly from those obtained by the other three groups and is shown as a separate curve. The results found by the four LEP experiments are labelled A, D, L and O in the figure legends. The size of the symbol for the LEP 2 point is larger than the statistical uncertainty for QCD events. Systematic terms were generally found to dominate the statistical ones for the experimental measurements shown in Fig. 7 .
Coherence reduces the mean soft gluon multiplicity in the parton shower.
It is generally expected that coherence will lead to a reduction in the mean hadron multiplicity as well. Thus, a measurement of at LEP 2 could help to establish the existence of coherence phenomena in the data. Overall, the models are seen to be in general agreement with each other. Some of the more notable exceptions to this agreement are discussed below. This feature is also observed at the Z energy.