s4h-probability-base-rate-anchoring

s4h-probability-base-rate-anchoring is a skill for Claude Code from human-avatar/skills-for-humanity. It costs 64 tokens per session (1,038 once invoked), scanned A, original, MIT.

A method for starting an estimate with the historical frequency of similar events before adjusting for details of the current case. This historical frequency is called the base rate.

In plain words
What is it for?
Use it to forecast outcomes, test an optimistic estimate, and compare a situation with a relevant reference group.
Why use it?
It prevents unusual details or optimism from overshadowing what normally happens in comparable situations.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: names the AskUserQuestion tool.

Part of the skills-for-humanity plugin — 197 skills, 1 hook shipped together

Good fit Use it to forecast outcomes, test an optimistic estimate, and compare a situation with a relevant reference group.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/human-avatar/skills-for-humanity/s4h-probability-base-rate-anchoring
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 human-avatar/skills-for-humanity --skill s4h-probability-base-rate-anchoring
Clone the repo
git clone --depth 1 https://github.com/human-avatar/skills-for-humanity

Made for: Claude Code.

Or install skills-for-humanity, the plugin that ships this one along with the rest of its 197 skills, 1 hook.

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.

agentmods badge for s4h-probability-base-rate-anchoring

README.md
[![agentmods](https://agentmods.dev/badge/skills/human-avatar/skills-for-humanity/s4h-probability-base-rate-anchoring/github.svg)](https://agentmods.dev/skills/human-avatar/skills-for-humanity/s4h-probability-base-rate-anchoring)
Your own site
<a href="https://agentmods.dev/skills/human-avatar/skills-for-humanity/s4h-probability-base-rate-anchoring"><img src="https://agentmods.dev/badge/skills/human-avatar/skills-for-humanity/s4h-probability-base-rate-anchoring/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.

agentmods 80×15 button for s4h-probability-base-rate-anchoring

Your own site · 80×15
<a href="https://agentmods.dev/skills/human-avatar/skills-for-humanity/s4h-probability-base-rate-anchoring"><img src="https://agentmods.dev/badge/skills/human-avatar/skills-for-humanity/s4h-probability-base-rate-anchoring.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 64 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,038 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00064 $0.01038
Opus 5 $0.00032 $0.00519
Sonnet 5 $0.00013 $0.00208
Haiku 4.5 $0.00006 $0.00104

Measured 9d ago against content hash caa9077889a5, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

s4h-probability-base-rate-anchoring 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 9d 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.

skills/s4h-probability-base-rate-anchoring/SKILL.md · 90 lines

How it starts

The opening of the file, as written. The whole thing — 90 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Probability Base Rate Anchoring

The most common forecasting error is treating every situation as unique and ignoring what usually happens. Kahneman called this neglecting the outside view. Before adjusting for what makes this situation special, you must first establish what happens in situations like this one. The base rate is the outside view — the answer to "what fraction of attempts like this one succeed?" — and it is almost always more informative than inside-view reasoning about this particular case.


Your Process

Step 1: State the Prediction or Estimate Name the specific outcome being predicted and the current estimate or intuition. What is being forecast and at what implied probability?

Framing check: Confirm the specific prediction before continuing. State what you've identified — the outcome being forecast, the current intuitive estimate, and the time horizon — in one sentence, then use AskUserQuestion:

  • Question: "I'm reading this as: [your one-sentence framing of the prediction and implied probability]. Is that right?"
  • Header: "Framing"
  • Options:
    • Yes — proceed — framing is correct
    • Adjust — one element is off; user will correct it before you continue
    • Reframe — different situation than read; incorporate the correction before proceeding

Step 2: Find the Reference Class What category of similar situations does this belong to? This is the most important and contested step. The reference class should be: (a) large enough to have stable base rates, (b) genuinely similar in the ways that matter, (c) not cherry-picked to flatter the prediction. If multiple reference classes apply, note them all.

Step 3: Find the Base Rate How often does this outcome actually occur in that reference class? Use historical data where available. If the exact rate is unknown, estimate a range from the most similar data available. This is the outside view — state it plainly, even if it is uncomfortable.

Step 4: Adjust for Differentiating Factors What specific, verifiable features of this situation distinguish it from the reference class? For each: does it push the probability up or down from the base rate? Explicitly consider factors that cut against your prior, not only those that support it.

Read the full file on GitHub · 90 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.

  1. 9d ago First seen · 90 lines · 64 tokens per session scan A caa9077889a5

Subscribe to this mod's changes

s4h-probability-base-rate-anchoring is a skill published in the GitHub repository human-avatar/skills-for-humanity (223 stars, last pushed 1mo ago), licensed MIT. It adds 64 tokens to every session and 1,038 once invoked, about $0.0003 per session on Opus 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 2026-09-03.

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