Market Sizer

market-sizer

Agent: Product Manager

L2 product manager (multi-instance) responsible for customer discovery, requirements extraction, sprint planning, backlog management, and go-live approval. Bridges customer needs and engineering delivery.

Department ethos: ideal-product.md

Skill Description

Sizes the total addressable, serviceable, and obtainable market for a product opportunity using top-down and bottom-up estimation methods.

When to Use

• When a new product opportunity needs quantified market context before entering the roadmap
• When leadership requests a revenue ceiling estimate to prioritize between competing initiatives
• When an existing market sizing is stale (older than two quarters) or based on assumptions that have shifted due to competitive moves or regulatory changes

Workflow

1. Define the market boundary: Identify the target customer segment, geography, and use case. Exclude adjacent segments that the product cannot credibly serve today. Deliverable: one-paragraph market definition with explicit inclusion and exclusion criteria.
2. Estimate TAM (top-down): Pull industry reports, analyst estimates, and public filings to calculate the total addressable market in annual revenue terms. Cross-check at least two independent sources. Deliverable: TAM figure with source citations and confidence rating (high/medium/low).
3. Estimate SAM (bottom-up): Narrow TAM to the segment reachable with the current product capabilities, pricing model, and go-to-market channels. Multiply estimated reachable accounts by average contract value. Deliverable: SAM figure with assumptions table.
4. Estimate SOM: Apply realistic penetration assumptions based on competitive intensity, sales capacity, and time horizon (typically 3 years). Deliverable: SOM figure with penetration rate justification.
5. Triangulate and stress-test: Compare top-down and bottom-up estimates. Flag any divergence greater than 2x and investigate. Run sensitivity analysis on the two most uncertain assumptions. Deliverable: summary table showing TAM/SAM/SOM with confidence intervals.
6. Package for decision-makers: Assemble a one-page market sizing brief suitable for inclusion in a PRD, investment memo, or roadmap review. Deliverable: formatted brief with key figures, assumptions, sources, and recommendation on whether the opportunity clears the minimum threshold.

Anti-Patterns

• Single-source sizing: Relying on one analyst report without cross-validation. Why: Analyst methodologies vary widely; a single source can overstate or understate by 3-5x, leading to misallocated resources.
• TAM-only thinking: Presenting the total addressable market as if it were capturable revenue. Why: TAM ignores competitive dynamics, distribution constraints, and product gaps, giving leadership a dangerously inflated picture.
• Static snapshots: Sizing the market once and never revisiting as conditions change. Why: Markets shift with new entrants, regulation, and technology changes; stale numbers silently corrupt downstream prioritization decisions.

Output

On success: A market sizing brief containing TAM, SAM, and SOM figures with confidence intervals, an assumptions table, source citations, and a go/no-go recommendation -- formatted for embedding in a PRD or roadmap review deck.

On failure: Report which estimates could not be completed (missing data sources, unreliable segment definitions, irreconcilable top-down vs. bottom-up gap), what was attempted, and recommend specific data acquisitions or customer interviews to close the gaps.

Related Skills

• backlog-groomer — sibling skill under the same agent — combine with backlog-groomer for end-to-end coverage
• backlog-populator — sibling skill under the same agent — combine with backlog-populator for end-to-end coverage
• customer-discovery-planner — sibling skill under the same agent — combine with customer-discovery-planner for end-to-end coverage
• demand-validator — sibling skill under the same agent — combine with demand-validator for end-to-end coverage
• dependency-mapper-review — sibling skill under the same agent — combine with dependency-mapper-review for end-to-end coverage
• dependency-resolver — sibling skill under the same agent — combine with dependency-resolver for end-to-end coverage
• design-approval — sibling skill under the same agent — combine with design-approval for end-to-end coverage
• flow-designer-review — sibling skill under the same agent — combine with flow-designer-review for end-to-end coverage
• go-live-approver — sibling skill under the same agent — combine with go-live-approver for end-to-end coverage
• internal-demo-runner — sibling skill under the same agent — combine with internal-demo-runner for end-to-end coverage
• jtbd-to-stories — sibling skill under the same agent — combine with jtbd-to-stories for end-to-end coverage
• launch-checklist-runner — sibling skill under the same agent — combine with launch-checklist-runner for end-to-end coverage
• risk-register-builder — sibling skill under the same agent — combine with risk-register-builder for end-to-end coverage
• story-writer — sibling skill under the same agent — combine with story-writer for end-to-end coverage
• milestone-definer — sibling skill under the same agent — combine with milestone-definer for end-to-end coverage
• performance-budget-setter — sibling skill under the same agent — combine with performance-budget-setter for end-to-end coverage
• phase-planner — sibling skill under the same agent — combine with phase-planner for end-to-end coverage
• phase-scope-adjuster — sibling skill under the same agent — combine with phase-scope-adjuster for end-to-end coverage
• pmm-pre-briefer — sibling skill under the same agent — combine with pmm-pre-briefer for end-to-end coverage
• requirements-extractor — sibling skill under the same agent — combine with requirements-extractor for end-to-end coverage
• roadmap-placer — sibling skill under the same agent — combine with roadmap-placer for end-to-end coverage
• scope-boundary-setter — sibling skill under the same agent — combine with scope-boundary-setter for end-to-end coverage
• spec-translator — sibling skill under the same agent — combine with spec-translator for end-to-end coverage
• sprint-planner — sibling skill under the same agent — combine with sprint-planner for end-to-end coverage
• sprint-reviewer — sibling skill under the same agent — combine with sprint-reviewer for end-to-end coverage
• support-pre-briefer — sibling skill under the same agent — combine with support-pre-briefer for end-to-end coverage
• third-party-integrator-review — sibling skill under the same agent — combine with third-party-integrator-review for end-to-end coverage
• uat-coordinator — sibling skill under the same agent — combine with uat-coordinator for end-to-end coverage
• user-researcher — sibling skill under the same agent — combine with user-researcher for end-to-end coverage