A comparison of the retention fraction from the N-body models (with r_v = 1.0 pc) with the analytic estimate. The limits from our analytic estimate, Eq. (6), are represented by a shaded area delimiting the escape radius from 0 pc (solid line) to the tidal radius (dashed line) determined from Eq. (4). We also include the curve for an escape radius of 10 pc (dotted line) and the virial radius (dashdotted line). The squares and crosses represent the retention fraction from our numerical simulations in the half-mass and tidal radius, respectively.