  We propose a numerical criterion which can be used to obtain accurate and
reliable values of the ordering temperatures and critical exponents of spin
glasses. Using this method we find an value of the ordering temperature for the
$\pm J$ Ising spin glass in three dimensions which is definitely non-zero and
in good agreement with previous estimates. We show that the critical exponents
of three dimensional Ising spin glasses do not appear to obey the usual
universality rules.
