  We compare our latest single and binary stellar model results from the
Cambridge STARS code to several sets of observations. We examine four stellar
population ratios, the number of blue to red supergiants, the number of
Wolf-Rayet stars to O supergiants, the number of red supergiants to Wolf-Rayet
stars and the relative number of Wolf-Rayet subtypes, WC to WN stars. These
four ratios provide a quantitative measure of nuclear burning lifetimes and the
importance of mass loss during various stages of the stars' lifetimes. In
addition we compare our models to the relative rate of type Ib/c to type II
supernovae to measure the amount of mass lost over the entire lives of all
stars. We find reasonable agreement between the observationally inferred values
and our predicted values by mixing single and binary star populations. However
there is evidence that extra mass loss is required to improve the agreement
further, to reduce the number of red supergiants and increase the number of
Wolf-Rayet stars.
