  We present a calculation of the electroweak mixing parameter $\sin^2
\theta_{eff}^{lept}$ that incorporates known higher order effects, shares the
desirable convergence properties of the $\bar{MS}$ scheme, and has the
important theoretical advantage of being strictly independent of the
electroweak scale in finite orders of perturbation theory . We also show how
this formulation can be extended to the calculation of the W mass $M_W$. The
results provide accurate, scale-independent evaluations of these important
parameters, as functions of the Higgs boson mass $M_H$, and are compared with
previous calculations in order to analyze the scheme and scale dependence of
the electroweak corrections.
