We employ data taken by the JADE and OPAL experiments for an integrated QCD
study in hadronic e(+)e(-) annihilations at c.m.s. energies ranging from 3
5 GeV through 189 GeV. The study is based on jet-multiplicity related obser
vables. The observables are obtained to high jet resolution scales with the
JADE, Durham, Cambridge and cone jet finders, and compared with the predic
tions of various QCD and Monte Carlo models. The strong coupling strength,
alpha (s), is determined at each energy by fits of O(alpha (2)(s)) calculat
ions, as well as matched O(alpha (2)(s)) and NLLA predictions, to the data.
Matching schemes are compared, and the dependence of the results on the ch
oice of the renormalization scale is investigated. The combination of the r
esults using matched predictions gives
alpha (s)(M-Z0) = 0.1187(-0.0019)(+0.0034).
The strong coupling is also obtained, at lower precision, from O(alpha (2)(
s)) fits of the c.m.s. energy evolution of some of the observables. A quali
tative comparison is made between the data and a recent MLLA prediction for
mean jet multiplicities.