During the project, resources may not be as readily available. This can have an effect on the schedule. It is more accurate to assign activity duration until all resources have been assigned.
This process can be somewhat ambiguous considering there are moving parts. Labor and the time it takes can to complete can be difficult to estimate if and when constraints develop through the project life cycle. The duration can be estimated more accurately once deliverables become more understood.
Estimate Activity Durations: Inputs, Tools and Techniques, and Outputs. Reprinted from "A Guide to the Project Management Body of Knowledge (PMBOK) 5th ed" by Project Management Institute, 2013, p.166. Copyright 2013 by PMI.Inc, Reprinted without permission.
1. Organizational Process Assets (Input): an essay to explain estimate activity durations through historical data and lessons learned.
2. Three-point Estimating (Tools and Techniques): Homework problem from PMGT 613 involves determining the probability of finishing a project by a certain date. PERT uses three-point estimating, a technique for Estimate Activity Duration process
3. Expert Judgement (Tools and Techniques): A brief paper describing work organizations utilizing their subject matter experts to properly address Estimate Activity Durations.