mostly-harmless-guide

mostly-harmless-guide is a skill for Claude Code, Codex from wentorai/research-plugins. It costs 17 tokens per session (1,553 once invoked), scanned A, original, MIT.

A practical guide and replication code for methods from the economics book *Mostly Harmless Econometrics*. It explains regression, instrumental variables, difference-in-differences, regression discontinuity, and related research methods.

In plain words
What is it for?
Use it to plan empirical studies, choose suitable estimators, apply core causal-inference methods, and interpret results in economics or other social sciences.
Why use it?
It helps researchers connect explanations of common econometric methods with working examples and decisions they must make when analysing real data.

Skill for Claude CodeCodex

Which agent this was written for is unclear — built for openclaw. Also seen: built for openclaw.

Good fit Use it to plan empirical studies, choose suitable estimators, apply core causal-inference methods, and interpret results in economics or other social sciences.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/wentorai/research-plugins/mostly-harmless-guide
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 wentorai/research-plugins --skill mostly-harmless-guide
Clone the repo
git clone --depth 1 https://github.com/wentorai/research-plugins

Made for: Claude Code, Codex.

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 mostly-harmless-guide

README.md
[![agentmods](https://agentmods.dev/badge/skills/wentorai/research-plugins/mostly-harmless-guide/github.svg)](https://agentmods.dev/skills/wentorai/research-plugins/mostly-harmless-guide)
Your own site
<a href="https://agentmods.dev/skills/wentorai/research-plugins/mostly-harmless-guide"><img src="https://agentmods.dev/badge/skills/wentorai/research-plugins/mostly-harmless-guide/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 mostly-harmless-guide

Your own site · 80×15
<a href="https://agentmods.dev/skills/wentorai/research-plugins/mostly-harmless-guide"><img src="https://agentmods.dev/badge/skills/wentorai/research-plugins/mostly-harmless-guide.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 17 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,553 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 $0.00017 $0.01553
Opus 5.5 $0.00007 $0.00621
Sonnet 5.5 $0.00003 $0.00311
Haiku 4.5 $0.00002 $0.00155

Measured 1mo ago against content hash 63e18b28c8a8, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

mostly-harmless-guide 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 1mo 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/analysis/econometrics/mostly-harmless-guide/SKILL.md · 133 lines

How it starts

The opening of the file, as written. The whole thing — 133 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Mostly Harmless Econometrics Guide

A skill providing replication code, explanations, and practical guidance for the econometric methods presented in Angrist and Pischke's "Mostly Harmless Econometrics" (MHE). Based on the mostly-harmless-replication repository (642 stars), this skill helps researchers understand and correctly apply core causal inference techniques.

Overview

"Mostly Harmless Econometrics" is one of the most influential applied econometrics textbooks, providing accessible explanations of the methods that dominate modern empirical research in economics and increasingly in other social sciences. This skill translates the book's core methods into practical guidance that the agent can use to help researchers design studies, select appropriate estimators, and interpret results correctly.

The skill covers regression, instrumental variables, difference-in-differences, regression discontinuity, and related methods, with emphasis on the practical decisions researchers face when applying these techniques to real data.

Regression Fundamentals

Ordinary Least Squares (OLS)

  • OLS provides the best linear approximation to the conditional expectation function
  • The regression anatomy theorem: each coefficient can be obtained from a bivariate regression of the outcome on the residualized regressor
  • Omitted variable bias formula: bias equals the effect of the omitted variable times its correlation with the included regressor
  • Control variables should be selected based on the conditional independence assumption, not on statistical significance
  • Robust standard errors (Huber-White) should be the default; cluster when observations are not independent

Regression Interpretation

  • The causal interpretation of regression requires the conditional independence assumption (CIA)
  • CIA states that treatment is as good as randomly assigned after conditioning on controls
  • Saturated models (fully interacted categorical variables) are always correctly specified
  • Linear regression with continuous variables approximates the true conditional expectation
  • Report both statistical and economic significance; a large t-statistic does not mean a large effect

Read the full file on GitHub · 133 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. 1mo ago First seen · 133 lines · 17 tokens per session scan A 63e18b28c8a8

Subscribe to this mod's changes

mostly-harmless-guide is a skill published in the GitHub repository wentorai/research-plugins (302 stars, last pushed 4mo ago), licensed MIT. It adds 17 tokens to every session and 1,553 once invoked, about $0.0001 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 2026-08-30.

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