Post-mortem (Lessons Learned Review)

A post-mortem — more formally called a lessons learned review or retrospective — is the process of systematically extracting knowledge from a completed project or phase and recording it in a form that can benefit future projects. A well-run post-mortem examines what happened against what was planned: where did cost and schedule outturns differ from forecasts, which risks materialised and which did not, which mitigation actions worked, and which decisions in hindsight proved to be wrong? The outputs feed the organisation's institutional knowledge base, inform future estimates and risk registers, and can be used to calibrate the three-point estimates used in future quantitative risk analyses.

Post-mortems are one of the most consistently neglected activities in project management. The reason is straightforward: they happen at the end, when the team has dispersed, the budget has been spent, and the project sponsor has moved on. There is no commercial incentive to invest time and money in an activity whose benefits accrue to future projects rather than the current one. Organisations that take lessons learned seriously build it into the project governance framework as a formal deliverable with budget, timing, and ownership — not an optional activity that gets scheduled and then cancelled.

For post-mortems to genuinely improve future practice, the lessons need to be specific and actionable. 'Communication was poor' is not an actionable lesson. 'The contractor's weekly progress reports consistently overstated earned value because there were no physical inspection requirements attached to the earning criteria — in future, earning rules should require photographic evidence or a site visit sign-off' is actionable. The test of a useful lesson is: could a project manager on a future project read this and change their behaviour? If not, the lesson has not been extracted at sufficient depth.