statistical-analysis

A guide to statistical analysis, including summaries of data, trends, unusual values, correlations, and tests of whether results are statistically meaningful.

In plain words
What is it for?
Use it to describe datasets, analyze trends, detect anomalies, compare variables, test hypotheses, and interpret statistical results with appropriate caution.
Why use it?
It helps choose measures that fit the data and avoid misleading conclusions caused by skewed distributions, outliers, or weak statistical evidence.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/anthropics/knowledge-work-plugins/statistical-analysis
Any agent
npx skills add anthropics/knowledge-work-plugins --skill statistical-analysis
Clone the repo
git clone --depth 1 https://github.com/anthropics/knowledge-work-plugins

Made for: Claude Code, Codex.

Per session 42 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,448 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00042 $0.02448
Opus 5 $0.00021 $0.01224
Sonnet 5 $0.00008 $0.00490
Haiku 4.5 $0.00004 $0.00245

Measured 2d ago against content hash 91a15cfc144e, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

statistical-analysis 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 2d 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.

Origin

Copies of this mod

3 near-identical copies found in the catalogue:

data/skills/statistical-analysis/SKILL.md · 246 lines

How it starts

The opening of the file, as written. The whole thing — 246 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Statistical Analysis Skill

Descriptive statistics, trend analysis, outlier detection, hypothesis testing, and guidance on when to be cautious about statistical claims.

Descriptive Statistics Methodology

Central Tendency

Choose the right measure of center based on the data:

Situation Use Why
Symmetric distribution, no outliers Mean Most efficient estimator
Skewed distribution Median Robust to outliers
Categorical or ordinal data Mode Only option for non-numeric
Highly skewed with outliers (e.g., revenue per user) Median + mean Report both; the gap shows skew

Always report mean and median together for business metrics. If they diverge significantly, the data is skewed and the mean alone is misleading.

Spread and Variability

  • Standard deviation: How far values typically fall from the mean. Use with normally distributed data.
  • Interquartile range (IQR): Distance from p25 to p75. Robust to outliers. Use with skewed data.
  • Coefficient of variation (CV): StdDev / Mean. Use to compare variability across metrics with different scales.
  • Range: Max minus min. Sensitive to outliers but gives a quick sense of data extent.

Percentiles for Business Context

Report key percentiles to tell a richer story than mean alone:

p1:   Bottom 1% (floor / minimum typical value)
p5:   Low end of normal range
p25:  First quartile
p50:  Median (typical user)
p75:  Third quartile
p90:  Top 10% / power users
p95:  High end of normal range
p99:  Top 1% / extreme users

Example narrative: "The median session duration is 4.2 minutes, but the top 10% of users spend over 22 minutes per session, pulling the mean up to 7.8 minutes."

Describing Distributions

Characterize every numeric distribution you analyze:

  • Shape: Normal, right-skewed, left-skewed, bimodal, uniform, heavy-tailed
  • Center: Mean and median (and the gap between them)
  • Spread: Standard deviation or IQR
  • Outliers: How many and how extreme
  • Bounds: Is there a natural floor (zero) or ceiling (100%)?

Read the full file on GitHub · 246 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. 2d ago First seen · 246 lines · 42 tokens per session scan A 91a15cfc144e

Subscribe to this mod's changes

statistical-analysis is a skill published in the GitHub repository anthropics/knowledge-work-plugins (23,791 stars, last pushed today), licensed Apache-2.0. It adds 42 tokens to every session and 2,448 once invoked, about $0.0002 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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