  Infrared and collinear events shapes are suited to directly probe properties
of hard QCD. They are traditionally used to measure the strong coupling and to
test the gauge structure of QCD. Perturbative predictions exist in several
variations all of which depend on the renormalisation scheme leading to large
theoretical uncertainties in the determination of $alpha_s$. To overcome this
dominating error more and more schemes for setting the renormalisation scale
are investigated. The application of RGI perturbation theory shows an
incredible small spread of $\alpha_s$ indicating a reduced uncertainty and
allows a measurement of the $\beta$-function directly from mean values.
