The text opposite explains why the Dynamic versus As-planned v As-built Critical Path Calculator:

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1. Is required to provide a factual assessment and determination of the Dynamic critical path and their sub-critical paths and the APAB actual critical path and sub-critical paths.

2. It explains the difference between the Dynamic CP's and the APAB CP's and explains: 

• why in retrospective delay analysis the APAB determination of criticality is preferred. 

• why for a prospective delay analysis a TIA method is preferred.​​​

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The text then explains how the Calculator gets its data from the baselines and the contemporaneous progress updates thereof the baselines.