An analysis of Precision Electroweak Measurements: Summer 98 Update

We update our analysis of precision electroweak measurements using the latest data announced at Moriond, March 1998. Possible oblique corrections from new physics are parametrized using the STU formalism of Ref.[1], and non-oblique corrections to the Zbb vertex are parametrized using the xi_b zeta_b formalism of Ref.[2]. The implications of the analysis on minimal SU(5) grand unification is discussed.