  We present a general method for extracting the Gell Mann-Low logarithmic
derivative of an effective charge of an observable directly from data as a mean
for empirically verifying the universal terms of the QCD $\beta$-function. Our
method avoids the biases implicit in fitting to QCD-motivated forms as well as
the interpolation errors introduced by constructing derivatives from discrete
data. We also derive relations between moments of effective charges as new
tests of perturbative QCD.
