PERT
Wednesday, December 02, 2009
12:14 PM
How (advanced) PERT works
Assign a normally-distributed probability distribution n(μ,σ) to each task: 
μ=mean completion time
σ=standard deviation of completion time
n(μ,σ)(t) = exp(-(t-μ)2/σ2)
Compute the PDF of the earliest start time and latest start time from the PDF of the task completion times! 
If we have two tasks in sequence, and they're independent, then the probability that the two take time t is the integral of the product of PDF(t1)*PDF(t2), for all t=t1+t2 (convolution).