Report of the Working Group on precision measurements

Precision measurements of electroweak quantities are carried out to test the Standard Model (SM). In particular, measurements of the top quark mass, mtop, when combined with precise measurements of the W mass, MW, and the weak mixing angle, sin2 bar θW, make it possible to derive indirect constraints on the Higgs boson mass, MH, via top quark and Higgs boson electroweak radiative corrections to MW. Comparison of these constraints on MH with the mass obtained from direct observation of the Higgs boson in future collider experiments will be an important test of the SM. In this report, the prospects for measuring the W parameters (mass and width) and the weak mixing angle in Run II are discussed, and a program for extracting the probability distribution function of MH is described