What are Project Baselines? - Google Project Mgmt
Google Project Management Interview Question and Answers - What are project baselines?
A baseline is a frozen, approved version of a plan used to measure actual performance. Without baselines, you can’t objectively say the project is ahead or behind, over or under budget, or whether a proposed change is material. Baselines create accountability, allow trend analysis, and force trade-off conversations to be explicit and evidence-based.
Core Baselines:
Practically every project I run has three primary baselines (the PMBOK trio), plus an important integrated view:
Scope Baseline
Components: project scope statement, Work Breakdown Structure (WBS), and WBS dictionary.
Purpose: defines what is included and what is not. Used to control scope creep and as the basis for acceptance.
Schedule Baseline
Components: approved milestone dates and detailed schedule (tasks, dependencies, durations) usually in a scheduling tool.
Purpose: baseline for milestone adherence and for calculating schedule variance / SPI.
Cost Baseline
Components: time-phased budget (costs allocated across schedule), plus contingency and management reserve accounting rules.
Purpose: the approved budget against which actual cost and EVM are measured.
Performance Measurement Baseline (PMB) — the integrated baseline
This is the integrated scope + schedule + cost baseline used for performance measurement (particularly for Earned Value Management). The PMB is the single reference that performance metrics (EV, PV, AC) map to.
Note: Some organizations also maintain a formal Quality Baseline (quality targets and acceptance criteria) and Benefits Baseline (expected KPIs and timelines for benefits realization). I treat those as critical companion baselines for business-driven projects.