Stars form in dense 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 are these estimations with respect to the number of stars observed. We simulated virialized clusters with King model distributions and from these clusters simulated observations. From these simulated observations we estimated cluster sizes and virial masses, and compared them to the model parameters of the distribution. The authors acknowledge support from the Bridgewater College Martin Science Research Institute.