Retrospective method
Windows and time-slice analysis
Cut the project into consecutive periods and identify what controlled completion in each one.
- Jurisdiction
- General method guidance, not jurisdiction specific
- Law and editions as at
- 3 August 2026
- Last reviewed
- 3 August 2026
- Editorial status
- Editorial draft, not yet independently reviewed
The question it answers
How did the critical path move through the job, and what moved it?
Retrospective analysis of a dynamic project where the controlling work changed over time and reasonable programme updates exist.
Minimum evidence
- Regular programme updates, or a defensible reconstruction of them
- Progress and as-built evidence for each window
- Contemporaneous narratives explaining changes
Window boundaries should follow the project, not the analyst. Data dates, major events, phase changes and contract milestones all make defensible boundaries. A boundary drawn immediately before an inconvenient event does not.
The heaviest information demand of any method sits here, and that is the honest reason it is not always used. Where the updates do not exist, say so and move to a method the record can support, rather than reconstructing updates and presenting them as contemporaneous.
Strengths
- Follows the job as it actually unfolded rather than as it was planned
- Recognises critical-path migration instead of assuming one path throughout
- Generally the most persuasive family where the records support it
Frequent failures
- Windows chosen arbitrarily, or chosen to place events conveniently
- Updates adopted without validation, so errors propagate through every slice
- The label used without the mechanics behind it
Mandatory caution
A window result is evidence of effect, not an automatic legal cause. Explain every window boundary, and test every update before relying on it.
Other methods
Where the record comes in
Every mechanism on this page turns on evidence: what happened, what was known and when. A record built as the job happens is worth more than any argument assembled afterwards. Construction Metric keeps that record automatically, from the messages, photographs and voice notes a site team already sends.
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The analysis on this site is only as fast as the evidence behind it. AI Metric builds bespoke systems for consultancies, contractors and claims teams: document and correspondence triage, event registers assembled from the project record, programme and cost reconciliation, and drafting support that always cites the document it came from. Built for review by your own experts, never to replace their judgement.
Do not overread this page
No method decides entitlement, and no method is court approved. A method is fit when it answers the relevant question with the reliable data available, respects the contract and the governing law, and survives alternative explanations. The choice must be explained and defended, not asserted.
General explanation of how contract mechanisms, analysis methods and legal principles generally work. It is not legal or contractual advice, not an opinion on any project, and no standard-form contract wording is reproduced anywhere on this site. Standard forms are routinely amended, so every default described here, including every time period, can be different on your project. Your executed contract, as amended, and the governing law and forum always control. Deadlines may already be running: if an event has occurred, preserve your position and take qualified advice.