  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.
