  Precision measurements, now and at a future linear electron-positron collider
(ILC), can provide indirect information about the possible scale of
supersymmetry. We illustrate the present-day and possible future ILC
sensitivities within the constrained minimal supersymmetric extension of the
Standard Model (CMSSM), in which there are three independent soft
supersymmetry-breaking parameters m_{1/2}, m_0 and A_0. We analyze the present
and future sensitivities separately for M_W, sin^2(theta_eff), (g-2)_mu, BR(b
-> s gamma), BR(B_s -> mu+ mu-), M_h and Higgs branching ratios. We display the
observables as functions of m_{1/2}, fixing m_0 so as to obtain the cold dark
matter density allowed by WMAP and other cosmological data for specific values
of A_0, tan beta and mu > 0. In a second step, we investigate the combined
sensitivity of the currently available precision observables, M_W,
sin^2(theta_eff), (g-2)_mu and BR(b -> s gamma), by performing a chi^2
analysis. The current data are in very good agreement with the CMSSM prediction
for tan beta = 10, with a clear preference for relatively small values of
m_{1/2} \sim 300 GeV. In this case, there would be good prospects for observing
supersymmetry directly at both the LHC and the ILC, and some chance already at
the Tevatron collider. For tan beta = 50, the quality of the fit is worse, and
somewhat larger m_{1/2} values are favoured. With the prospective ILC
accuracies the sensitivity to indirect effects of supersymmetry greatly
improves. This may provide indirect access to supersymmetry even at scales
beyond the direct reach of the LHC or the ILC.
