A common cause of risk is the scheduling and resource allocation activity.
Good planning can help to improve risk.
Once the project has begun it is important to monitor its progress and modify the plans. Estimation is the honest prediction of what is likely to happen. Estimates with well understood assumptions can be useful in the identification and control of risks of unachievable targets. Targets that are very pessimistic can give slack that can be used for reducing risks or coping with the effect of problems. However targets that ignore estimates may be unachievable.