This study examined factors that affect cost overruns for contractors on construction projects. The researchers analyzed data from over 1,000 construction projects to identify key risk factors. They found that poor cost estimation, unforeseen site conditions, and changes in project scope were the most significant predictors of cost overruns. Projects with these issues were much more likely to exceed their budgeted costs. The researchers concluded that improving cost estimation practices and better defining project requirements could help reduce contractors' financial risks.