Literature based hypotheses on the proportion of project management effort are created and tested with reported effort data from 117 projects by software supplier firms. The results support most of the literature based hypotheses, but some of the hypotheses are not supported. The supported hypotheses are the correlations between project management effort, project size, and team size. The unsupported hypotheses are the necessity of spending at least some project management effort on a project, and the insignificance of contract type. The conflict with previous studies and practical experience may be a result from market pressures and skewed reporting. The analysis implies that there is a pattern of inaccurate reporting of effort data and some possible explanations for the pattern are discussed. The results suggest that we do not properly understand the internal dynamics of supplier firms.