What is reference-class-forecaster?

A method for improving estimates by comparing a project with similar completed projects. This is called the outside view: it checks a plan against real reference examples instead of relying only on the project team’s internal forecast.

Use it to adjust cost, duration, and benefit estimates for projects such as transformations, product launches, capital work, or mergers. It produces ranges and flags that support funding decisions.

It helps expose optimism bias, where teams underestimate cost or time or overestimate benefits.

reference-class-forecaster — Skill for Claude Code by daddia

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add daddia/claude-for-strategy --skill reference-class-forecaster

Clone the repo

git clone --depth 1 https://github.com/daddia/claude-for-strategy

Made for: Claude Code.

Or install consulting, the plugin that ships this one along with the rest of its 9 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/daddia/claude-for-strategy/reference-class-forecaster/github.svg)](https://agentmods.dev/skills/daddia/claude-for-strategy/reference-class-forecaster)

Your own site

<a href="https://agentmods.dev/skills/daddia/claude-for-strategy/reference-class-forecaster"><img src="https://agentmods.dev/badge/skills/daddia/claude-for-strategy/reference-class-forecaster/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/daddia/claude-for-strategy/reference-class-forecaster"><img src="https://agentmods.dev/badge/skills/daddia/claude-for-strategy/reference-class-forecaster.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 73 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,866 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00073	$0.01866
Opus 5.5	$0.00029	$0.00746
Sonnet 5.5	$0.00015	$0.00373
Haiku 4.5	$0.00007	$0.00187

Measured 2mo ago against content hash 1a4e5e6984fc, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

reference-class-forecaster scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

consulting/skills/reference-class-forecaster/SKILL.md · 158 lines

How it starts

The opening of the file, as written. The whole thing — 158 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Reference Class Forecaster

When to use

Calibrate cost, duration, and benefit estimates using the outside view before inside-view narrative wins the room — capital projects, transformation programs, product launches, and M&A integration timelines.

Pairs naturally with /transformation:business-case, /corporate-strategy:evaluate-strategic-option, and /value-realisation:realisation-review calibration loops.

What this skill does not do

Does not replace sponsor judgment — produces adjusted ranges and explicit bias flags; strategist decides funding.
Does not invent a reference class — asks for comparables or uses sourced benchmarks; gaps tagged INPUT NEEDED.
Does not approve spend — output is decision support with [review] on every adjusted headline number.

Preconditions

Input	If missing
Inside-view estimate (cost, duration, benefit, or all three)	Ask — cannot forecast without a claim to calibrate
Project type and scale band	Ask or infer from context; label assumption
Comparable reference class (optional)	Build from user examples + tagged public benchmarks

Provisional mode

When no org-specific track record exists in profiles, use published reference-class medians (Flyvbjerg infrastructure/program data, sector benchmarks) tagged [model knowledge — verify] and confidence structured first pass.

Trust spine

Confidence bands (hypothesis-driven-analysis):
- High: ≥3 independent comparables in class; uplift applied with cited Green Book or org policy.
- Medium: 1–2 comparables or mixed quality; uplift stated with rationale.
- Low: Class named but thin evidence — directional adjustment only.
Analytical Rigor (mandatory): Inside vs outside view shown side by side; uplift arithmetic explicit.
Accountability gap: Adjusted range presented; inside-view retained for contrast — strategist picks which to fund against.
Per ../../references/trust-conventions.md for sourcing, [verify], and GATE before board finals.

Read the full file on GitHub · 158 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2mo ago First seen · 158 lines · 73 tokens per session scan A 1a4e5e6984fc

Subscribe to this mod's changes

reference-class-forecaster is a skill published in the GitHub repository daddia/claude-for-strategy (2 stars, last pushed 4mo ago), licensed MIT. It adds 73 tokens to every session and 1,866 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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Two visual modes — render a PR diff as an HTML page with each hunk annotated by principle, or check a UI change in a real browser (screenshots, console, network). Use for a visual/HTML diff report, "check the UI", or "screenshot before/after". Don't use for text-only feedback (/code-review), unit tests (/tdd), or full…

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reference-class-forecaster