1. A computer-implemented method of determining estimation variance associated with project planning, comprising: obtaining information associated with a project, said project comprising a plurality of tasks; determining initial estimates and estimate variances of the plurality of tasks from the information; obtaining actual measurements associated with a selected task from the plurality of tasks after said selected task is executed; computing a difference between an initial estimate associated with the selected task and the actual measurements; revising, using the computed difference, the initial estimates associated with remaining one or more tasks; and determining estimate variances of said remaining one or more tasks based on the revised estimates.