  We study the numerical effects of several renormalization schemes of the
Cabibbo-Kobayashi-Maskawa (CKM) quark mixing matrix on the top-quark decay
widths. We then employ these results to infer the relative shifts in the CKM
parameters |V_{tq}|^2 due to the quark mixing renormalization corrections,
assuming that they are determined directly from the top-quark partial decay
widths, without imposing unitarity constraints. We also discuss the
implications of these effects on the ratio R = Gamma(t -> Wb) / Gamma_t and the
determination of |V_{tb}|^2.
