Window Analysis

Window analysis is a retrospective delay analysis method that divides the project timeline into sequential periods (windows) — typically monthly or fortnightly — and analyses the movement of the critical path and Completion Date through each window. For each window, the analyst identifies which events drove critical path change, quantifying the delay impact per period and attributing causation.

The technique is particularly effective at handling concurrent delays and shifting critical paths, which are both difficult for single-event methods like TIA to manage. By tracking critical path evolution across windows, window analysis can distinguish between delay caused by Contractor-controlled risks and delay caused by Employer-controlled risks, even when both occur in overlapping periods. The SCL Delay and Disruption Protocol discusses window analysis among the preferred methods for retrospective delay assessment.

The practical requirement is good contemporaneous records: each window needs a reliable snapshot of the programme state at start and end, and the events occurring within each window must be identifiable and dated. Projects that have not maintained disciplined programme updates through delivery find window analysis difficult to apply credibly. The analysis also has a subjective component in how the windows are defined and how events within each window are attributed — which is why window analysis reports from different experts can produce different conclusions from the same underlying data.