  I derive precise results for absorbing-state phase transitions using exact
(numerically determined) quasistationary probability distributions for small
systems. Analysis of the contact process on rings of 23 or fewer sites yields
critical properties (control parameter, order-parameter ratios, and critical
exponents z and beta/nu_perp) with an accuracy of better than 0.1%; for the
exponent nu_perp the accuracy is about 0.5%. Good results are also obtained for
the pair contact process.
