Five most commonly used techniques to estimate activity duration,”1. Expert judgement relies on the knowledge of someone familiar with the tasks. 2. Analogous or top-down estimating bases the estimate on similar activities from a previous project. 3. Parametric estimates are quantitatively based estimates that typically calculate the rate times quantity. 4. Three point estimates use the most likely, optimistic, and pessimistic estimates to determine an average estimate.5. PERT uses the same estimates as the three point estimating technique

Five most commonly used techniques to estimate activity duration,”1. Expert judgement relies on the knowledge of someone familiar with the tasks. 2. Analogous or top-down estimating bases the estimate on similar activities from a previous project. 3. Parametric estimates are quantitatively based estimates that typically calculate the rate times quantity. 4. Three point estimates use the most likely, optimistic, and pessimistic estimates to determine an average estimate.5. PERT uses the same estimates as the three point estimating technique

but it calculates an expected value or weighted average estimate.”