tags: #refine #publish links: [[Estimation Techniques]] created: 2021-07-29 Thu --- # PERT https://en.wikipedia.org/wiki/Program_evaluation_and_review_technique An estimation technique using dependencies (Gantt chart styl) and statistical methods / probabilistic techniquest to improve accuracy. See also [[Three-point estimation]] - Events with predecessors and successors - Different time estimations, and a statistical method for combining them: - **optimisitic** - the minimum possible - **pessimistic** - the maximum possible - **most likely** - best estimate if everything proceeds as normal - **expected** - estimate accounting for things *not* proceeding as normal! (e.g. the average time expected if the task was repeated many times so encountered all outcomes) One can combine these task estimates to estimate overall project and likelihood of variance - see the Wikipedia page. The method also includes concepts of slack time, critical path, lead times, etc.