The nature of the electroweak bosonic loop corrections to which current
precision experiments are sensitive is explored. The set of effective
parameters \De x, \De y, and \eps, which quantify SU(2) violation in an
effective Lagrangian, is shown to be particularly useful for this purpose. The
standard bosonic corrections are sizable only in the parameter \De y, while
\De x and \eps are sufficiently well approximated by the pure fermion-loop
prediction. By analyzing the contributions to \De y it is shown that the
bosonic loop corrections resolved by the present precision data are induced by
the change in energy scale between the low-energy process muon decay and the
energy scale of the LEP1 observables. If the (theoretical value of the)
leptonic width of the W boson is used as input parameter instead of the Fermi
constant \GF, no further bosonic loop corrections are necessary for
compatibility between theory and experiment.Comment: 15 pages, latex, 6 uuencoded postscript figures, talk presented by G.
Weiglein at The Second German-Polish Symposium, New Ideas in the Theory of
Fundamental Interactions, Zakopane, September 199
