Scale-Independent Calculation of $\sin^2 \theta_{eff}^{lept}$

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.