Inputs to Perform Quantitative Risk Analysis

Evaluating project risks through numerical modelling allows Australian architectural practices to move beyond qualitative rankings and calculate exact financial and schedule risk exposure. Before running statistical simulations or decision tree models, practitioners must assemble robust empirical data. Under PMI PMBOK® standards and AS ISO 31000, the Perform Quantitative Risk Analysis process relies on four primary input categories that establish the rules, baseline data, external boundaries, and historical benchmarks required for accurate quantitative forecasting.

1. The Project Management Plan (Risk Management Plan)

The Project Management Plan, specifically the Risk Management Plan sub-component, serves as the foundational instruction manual for quantitative analysis. It establishes the governing methodology, defining which analytical techniques (such as Monte Carlo simulations, sensitivity analysis, or decision tree analysis) and software tools are authorised. Furthermore, it defines practice risk thresholds, target confidence levels (such as an 80% certainty target for cost estimates), and the allocated budget and schedule for conducting quantitative risk studies.

2. Project Documents

Project Documents provide the granular, real-world data and baseline estimates needed to build mathematical risk models. Key project documents utilised during quantitative risk analysis include:

• Assumption Log: Tracks baseline premises (e.g., assumed council DA approval times or soil load capacities) to quantify the impact of assumption variance.
• Basis of Estimates & Cost Estimates: Details how cost figures were derived and their inherent variability, forming the starting point for cost risk modelling.
• Cost & Schedule Forecasts: Measures estimate-at-completion metrics against quantitative results to assess financial target confidence.
• Duration Estimates & Milestone List: Supplies activity timeframes and critical schedule checkpoints to calculate schedule risk.
• Resource Requirements: Captures labour and specialist consultant constraints that influence duration and cost volatility.
• Risk Register & Risk Report: Provides the core list of prioritised risks, initial probability/impact ratings, and systemic risk sources to quantify.

3. Enterprise Environmental Factors (EEFs)

Enterprise Environmental Factors incorporate external macro-conditions and internal organisational constraints that lie outside the immediate control of the project team. In Australian practice, key EEFs include National Construction Code (NCC) regulatory updates, local council planning overlays, published industry cost benchmarks (such as Australian Institute of Quantity Surveyors data), market supply chain volatility, and local labour availability. EEFs ensure that quantitative risk models reflect real-world market realities.

4. Organisational Process Assets (OPAs)

Organisational Process Assets represent the internal historical intelligence and standardised templates of the architectural practice. OPAs include historical risk registers from completed projects, post-occupancy evaluation databases, standardised probability distribution guidelines (such as PERT or Triangular distributions), and lessons learned repositories. Utilising OPAs prevents practices from creating models from scratch, grounds estimations in past performance, and increases simulation accuracy.

Looking Ahead in This Series

This overview sets the stage for mastering quantitative project controls. In the following posts, we will talk about each of these inputs in detail, exploring how to leverage specific project documents and practice assets to build defensible numerical models.

Professional Competency and CPD Alignment

Mastering quantitative inputs strengthens practice governance, protects fixed-fee margins, and aligns directly with the National Standard of Competency for Architects (NSCA 2021) across Practice Management and Project Delivery units.