srm-check

srm-check is a skill for Claude Code from ai-analyst-lab/ai-analyst-plugin. It costs 91 tokens per session (2,163 once invoked), scanned A, original, MIT.

A safety check for A/B tests and other experiments. Sample Ratio Mismatch means that the treatment and control groups do not have the expected sizes, which can signal a broken experiment.

In plain words
What is it for?
Checking experiment data before calculating treatment effects or comparing outcomes.
Why use it?
It can stop analysis before results are compared when the experiment's group assignment appears unreliable.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the ai-analyst-plus plugin — 44 skills, 1 command, 13 agents shipped together

Good fit Checking experiment data before calculating treatment effects or comparing outcomes.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/ai-analyst-lab/ai-analyst-plugin/srm-check
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 ai-analyst-lab/ai-analyst-plugin --skill srm-check
Clone the repo
git clone --depth 1 https://github.com/ai-analyst-lab/ai-analyst-plugin

Made for: Claude Code.

Or install ai-analyst-plus, the plugin that ships this one along with the rest of its 44 skills, 1 command, 13 agents.

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 srm-check

README.md
[![agentmods](https://agentmods.dev/badge/skills/ai-analyst-lab/ai-analyst-plugin/srm-check.svg)](https://agentmods.dev/skills/ai-analyst-lab/ai-analyst-plugin/srm-check)
Your own site
<a href="https://agentmods.dev/skills/ai-analyst-lab/ai-analyst-plugin/srm-check"><img src="https://agentmods.dev/badge/skills/ai-analyst-lab/ai-analyst-plugin/srm-check.svg" alt="Measured on agentmods" height="20"></a>
Per session 91 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,163 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 warn 7 Sept 2026
SkillSpector: 1 finding, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium Excessive Agency · line 174
    Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.
    Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
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 $0.00091 $0.02163
Opus 5 $0.00046 $0.01081
Sonnet 5 $0.00018 $0.00433
Haiku 4.5 $0.00009 $0.00216

Measured 8d ago against content hash 8bb1e73eec23, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

srm-check 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 8d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/srm.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

ai-analyst-plus/skills/srm-check/SKILL.md · 178 lines

How it starts

The opening of the file, as written. The whole thing — 178 lines — stays where its author put it; the contents beside it link to each section on GitHub.

If the skill install path cannot be resolved (some sandboxed environments): read the script file(s) from this skill, write a copy into a scripts/ folder inside the working folder, and run from there. The scripts are self-contained.

Skill: SRM Check (Sample Ratio Mismatch)

Purpose

Automatically detect Sample Ratio Mismatch in experiment data before any analysis proceeds. SRM is a randomization integrity check — if the treatment/control split deviates significantly from the expected ratio, the experiment is compromised and results cannot be trusted. This skill acts as a safety gate that blocks analysis when randomization is broken.

When to Use

Apply this skill when:

  1. Loading any experiment or A/B test dataset — auto-fire on detection of treatment/control columns (e.g., variant, group, treatment, arm, experiment_group)
  2. Before any treatment effect calculation — SRM must pass before comparing outcomes
  3. When the Experiment Analyzer agent starts — first step of any experiment analysis workflow

This skill auto-fires on experiment data detection. Do NOT wait to be asked.

Instructions

What Is SRM?

Sample Ratio Mismatch (SRM) occurs when the observed ratio of users in treatment vs. control deviates significantly from the expected ratio. For a 50/50 experiment with 10,000 users, you expect ~5,000 in each group. If you see 5,500 vs. 4,500, something is wrong with randomization.

SRM CHECK
━━━━━━━━━━
Expected ratio:  50/50 (or whatever was designed)
Observed ratio:  [actual counts]
Test:            Chi-squared goodness-of-fit
Decision:        PASS (proceed) or BLOCK (halt analysis)

Why SRM matters: If randomization is broken, treatment and control groups are NOT comparable. Any observed difference in outcomes could be caused by the broken randomization, not the treatment. SRM is the single most important validity check in experimentation.

Detection Logic

Step 1: Identify the experiment column

Scan the dataset for columns that indicate experiment assignment. Look for:

  • Column names: variant, group, treatment, control, arm, experiment_group, test_group, bucket, condition
  • Column values: binary (0/1, control/treatment, A/B), or small number of distinct values (< 10)
  • User language: phrases like "A/B test", "experiment", "treatment vs control", "randomization"
  • Metadata: check for experiment config files in .knowledge/experiments/

Read the full file on GitHub · 178 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 8d ago First seen · 178 lines · 91 tokens per session scan A 8bb1e73eec23

Subscribe to this mod's changes

srm-check is a skill published in the GitHub repository ai-analyst-lab/ai-analyst-plugin (32 stars, last pushed 11d ago), licensed MIT. It adds 91 tokens to every session and 2,163 once invoked, about $0.0005 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 2026-08-30.

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