  The next-next-to-leading order QCD corrections to the e+e- annihilation into
hadrons are considered. The stability of the predictions with respect to change
of the renormalization scheme is discussed in detail for the case of five, four
and three active quark flavors. The analysis is based on the recently proposed
condition for selecting renormalization schemes according to the degree of
cancellation that they introduce in the expression for the scheme invariant
combination of the expansion coefficients. It is demonstrated that the scheme
dependence ambiguity in the predictions obtained with the conventional
expansion is substantial, particularly at lower energies. It is shown however,
that the stability of the predictions is greatly improved when QCD corrections
are evaluated in a more precise way, by utilizing the contour integral
representation and calculating numerically the contour integral.
