Stars form in clusters within giant molecular clouds. Spectroscopic observations can reveal radial velocities from which virial masses can be estimated. The question we are investigating is how accurate these estimates are with respect to the number of stars observed. We simulated virialized clusters with King model distributions and from these clusters we simulated mock observations. From these observations cluster sizes and virial masses are estimated, and empirical distribution functions are constructed. A confidence interval table is produced considering the number of objects observed and the ratio of velocity dispersion to observational uncertainty.
