of the Milky Way galaxy. Numerous groups have used this survey to identify new massive stellar cluster candidates. Follow up study of
these candidates indicate about half are true, bound clusters (theknown). The remaining are 'false positives': high density fields of unassociated stars, mimicking a true cluster. What is not so easy to estimate is the number of 'false negatives' from present surveys. These are clusters which exist, but are not detected in current searches (known unknowns). A cluster might not be detected because the core is not concentrated enough, it is highly extinguished, or there may be significant biases in the selection criteria used. In order to derive critical characteristics of the Milky Way's massive cluster population, such as the cluster mass function and cluster lifetimes, one must estimate the characteristics of stellar clusters that are presently missed by current surveys. Our group has taken on this daunting task to constrain the known unknowns via a sophisticated stellar cluster image simulation tool, MASSCLEAN, we've developed. I will present our preliminary efforts that make the first attempt to understand the biases of current searches, provide guidance on preparing more effective searches and our goal of ultimately estimating the characteristics of the massive cluster population of the entire Milky Way galaxy.
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