A simulation study that used 3,000 computer-generated event streams with known behavior rates, interval durations, and session durations was conducted to test whether the main and interaction effects of true rate and interval duration affect the error level of uncorrected and Poisson-transformed (i.e., "corrected") count as estimated by partial-interval recording. For both count estimates, shorter intervals and lower true rates resulted in less error than longer intervals and higher rates. For all conditions tested, Poisson-corrected estimates were more accurate than uncorrected estimates. Therefore, using Poisson-corrected estimates and short intervals are recommended when partial-interval recording is used to estimate counts. Generality of results might be restricted to events that are about 1-s long. A URL was provided to aid in the computation of corrected counts.