Risk is the variability of outcome.  For any project, the  estimates of time and costs that are made during the initial and continuing stage always change.  Accepting the fact that the estimate would change and to encounter the difficulty caused by the change is the risk analysis

.The Project Management Institute (PMI) defines Project Risk Management as the “systematic process of identifying, analyzing, and responding to uncertain events or conditions in a project.” Quantitative risk analysis is defined as, “the process of analyzing the consequences of risk on project objectives”. Monte Carlo simulation is commonly used to assess the project risk. 

The risks associated with the cost or resources can be managed in a generic simulation software described elsewhere.  In case of a project, the scheduling is not a simple additive algorithm.  The concept of the critical path is the central theme in any scheduling algorithm.  A few project management software is designed specifically to estimate the scheduling risk.  Examples are presented.

@ risk for project : It is an exhaustive package for serious investigation about the risk.   A number of probability distribution can be assumed.  Concepts like probabilistic branching that allows to assume multiple critical path during simulation is allowed in the algorithm.  Similarly probabilistic calendar to account for the weather can be assumed.  A view of the types of the risk distribution in @ Risk is presented

Pert Master: Pert master is one of the premium program for risk analysis.  MS Project data can be easily imported for further study.  An output from Pert Master is presented

Risky Project: This is also a standard package for risk analysis.  The result after the simulation is presented in the following manner.

The Gantt chart in Risky project shows the risk distribution of each task as pointed out in the figure.  Like the previous package the software is capable to import data from MS Project and others with ease.  Risky project can also send results to Vanguard - a quantitative optimization software for further analysis like decision tree.

Ranger:   Ranger is an economical solution for risk analysis.  It is a MS Project add-on.  It can be called from the MS project.  It uses several custom fields of MS Project to store data.  It uses a triangular distribution for time or cost variation as presented here that should be adequate for most purpose.