3.1 Cost Estimating, Budgeting & Financial Reserves

🎯 Key PMI PMP® Exam Takeaways

• Analogous estimating is fast and low-cost for early phases; Bottom-Up is the most accurate and definitive but time-intensive.
• PERT Beta expected duration/cost formula: (Optimistic + 4(Most Likely) + Pessimistic) / 6.
• Contingency Reserves cover 'known-unknowns' (identified risks) and reside inside the approved Cost Baseline.
• Management Reserves cover 'unknown-unknowns' (unforeseen risks), reside outside the Cost Baseline, and require CCB approval to allocate.

Developing an accurate project budget requires selecting appropriate estimating techniques suited to project maturity. Early in initiation, Analogous estimating uses historical project comparables for rough order-of-magnitude estimates. As requirements detail matures, Parametric estimating applies statistical relationships, and Bottom-Up estimating aggregates detailed work package estimates for definitive precision.

To account for uncertainty, project managers utilize Three-Point estimating. While simple triangular distributions average the three estimates, the standard PERT Beta distribution applies a 4x weighting to the Most Likely estimate: (O + 4M + P) / 6.

Budget governance establishes distinct financial reserves. Contingency Reserves are calculated to address identified risks in the risk register; they are managed directly by the project manager and form part of the approved Cost Baseline. Management Reserves address unforeseen emerging risks (unknown-unknowns), sit outside the Cost Baseline, and require formal Change Control Board approval to access.

⚠️ Common PMI Exam Traps

• Drawing from Management Reserve for identified risks; identified risks are funded exclusively from Contingency Reserves.
• Confusing the Cost Baseline with the Total Project Budget; Cost Baseline + Management Reserve = Total Project Budget.