📐 PMP Estimating — Complete Exam Study Guide

Estimating is the process of quantifying the likely amount of resources, time, or cost required to complete project work. It is NOT guessing — it is informed prediction based on data, experience, and judgment.

In the PMP context, estimating applies to three key areas:

• 🕐 Schedule — How long will activities take?
• 💰 Cost — How much money is needed?
• 👷 Resources — How many people, equipment, materials?

When Does Estimating Happen?

Poor estimating is one of the top causes of project failure. The PMP exam expects you to recognize the consequences of inaccurate estimates and the PM's responsibility.

Estimates vary in accuracy depending on the project phase and available information.

Progressive Elaboration of Estimates

As the project progresses and more information becomes available, estimates are refined. This is rolling wave planning in action.

PMBOK 7 shifted from process groups to performance domains and principles. Estimating now spans multiple domains:

• 📋 Planning — Creating cost and schedule baselines
• ⚙️ Project Work — Monitoring actuals vs. estimates
• 📦 Delivery — Estimating value and features (Agile)
• 📊 Measurement — EVM, forecasting, variance analysis

Analogous Estimating uses historical data from similar past projects to estimate the current project. It is a form of expert judgment supported by historical information.

Parametric Estimating uses a statistical relationship between historical data and other variables (parameters) to calculate an estimate.

Bottom-Up Estimating involves estimating the cost/duration of individual work packages or activities and then aggregating (rolling up) to get the total project estimate.

Requires a detailed WBS (Work Breakdown Structure).

Three-Point Estimating uses three estimates to define an approximate range for an activity's duration or cost. It accounts for uncertainty and risk.

Where: O = Optimistic, M = Most Likely, P = Pessimistic

Expert Judgment involves consulting individuals or groups with specialized knowledge, training, or experience to estimate cost, duration, or resources.

Expert judgment is used as a tool in nearly every estimating technique — it is rarely used alone.

Reserve Analysis is used to determine the amount of contingency and management reserve needed to handle uncertainty in project estimates.

Cost estimates must account for all types of costs in a project:

Cost of Quality (CoQ) is the total cost of all efforts related to quality — both conformance and non-conformance costs.

Vendor Bid Analysis (also called Bid/Quote Analysis) examines bids and quotes from vendors to determine whether the proposed prices are reasonable and within the project budget.

• Compares multiple vendor bids for the same scope
• Identifies outliers (too high or too low)
• Considers total cost of ownership, not just purchase price

These three concepts are heavily tested on the PMP exam — many candidates confuse them.

Resource estimating determines the types and quantities of human resources, equipment, and materials required to complete project work.

Process: Estimate Activity Resources (Schedule Management)

• What type of resource? (Skill level, specialty)
• How many? (Number of personnel, machines)
• When? (Availability, calendar)
• Where? (Location-based resource availability)

Resource Histogram

A bar chart showing resource usage over time. Helps identify resource overallocation.

Velocity is the amount of work a team completes in a sprint, measured in story points. Used in Agile to forecast future sprint capacity.

The Basis of Estimates (BOE) is a document that explains HOW estimates were developed — the assumptions, constraints, and methodology used.

Think of it as the "show your work" document for estimates.

Different sources list slightly different ranges. The PMP exam tests the general concept — not exact numbers. Know the pattern:

Earned Value Management (EVM) integrates scope, schedule, and cost to measure project performance against the baseline.

Forecasting estimates the future cost to complete remaining work based on current performance.

Story Points are a unit of measure for expressing the overall effort or complexity required to fully implement a product backlog item (user story). They are relative, not absolute (not hours).

Planning Poker is a consensus-based estimating technique used in Agile teams. Each team member selects a card with a story point value. Cards are revealed simultaneously to prevent anchoring bias.

How It Works

1. Product Owner reads a user story
2. Team members ask clarifying questions
3. Each member selects a card (secretly)
4. All cards revealed at the same time
5. Outliers explain their reasoning
6. Process repeats until consensus is reached

T-Shirt Sizing is a quick, relative estimating technique using clothing sizes (XS, S, M, L, XL, XXL) to categorize work items. Used for high-level backlog grooming.

Affinity Estimating is a fast technique where the team groups user stories into buckets (like T-shirt sizes or point groups) by similarity — without detailed discussion of each item individually.

How It Works

1. Write each backlog item on a card
2. Team silently sorts cards into groups by relative size
3. Label groups with point values or T-shirt sizes
4. Discuss outliers and re-sort as needed

Click any keyword below for a quick definition:

Your notes are auto-saved to this browser. Type freely.