statistical-power

A method for calculating how many participants, samples, or repeated measurements a study needs, or what effect a chosen sample can reliably detect. Statistical power is the chance of detecting a real effect of a chosen size.

In plain words
What is it for?
Use it for sample-size planning, minimum detectable effect calculations, power curves, grant or ethics applications, and preregistration.
Why use it?
It helps avoid studies that are too small to answer their question or unnecessarily large and costly before data collection begins.

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/xintaofei/codeg/statistical-power
Any agent
npx skills add xintaofei/codeg --skill statistical-power
Clone the repo
git clone --depth 1 https://github.com/xintaofei/codeg

Made for: Claude Code, Codex.

Per session 190 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,445 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 $0.00190 $0.03445
Opus 5 $0.00095 $0.01723
Sonnet 5 $0.00038 $0.00689
Haiku 4.5 $0.00019 $0.00345

Measured 3d ago against content hash 40f9c8bd0cc9, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

statistical-power 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 3d ago.

The scan reads SKILL.md. This mod also ships 2 executable files (scripts/power.py, scripts/simulate_power.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.

src-tauri/science/skills/statistical-power/SKILL.md · 199 lines

How it starts

The opening of the file, as written. The whole thing — 199 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Statistical Power & Sample Size

Overview

Power analysis answers one of the most consequential questions in study planning: how large a sample do you need to reliably detect an effect of a given size, and what could you detect with the sample you can afford? An underpowered study wastes resources and produces inconclusive or irreproducible results; an overpowered one wastes participants, money, and (in clinical work) exposes more people to risk than necessary. Getting this right before data collection is the single highest-leverage statistical decision in a project.

Four quantities are locked together for any given test: sample size (n), effect size, significance level (α), and power (1 − β). Fix any three and the fourth is determined. Every calculation in this skill is some rearrangement of that relationship.

This skill covers the two ways to do power analysis:

  • Closed-form formulas (fast, exact for standard tests) — see references/closed_form_recipes.md.
  • Simulation / Monte Carlo (works for any design or model you can simulate and analyze) — see references/simulation_based_power.md.

For choosing and converting effect sizes — usually the hardest part — see references/effect_sizes.md.

When to Use This Skill

  • Determining required sample size before collecting data (a priori power analysis)
  • Finding the minimum detectable effect (MDE) for a fixed, already-determined sample size
  • Producing power curves (power vs. n, or power vs. effect size) for a grant or protocol
  • Justifying a sample size for an IRB submission, grant, or pre-registration
  • Powering designs with unequal group sizes or non-1:1 allocation
  • Powering anything without a textbook formula (mixed models, logistic/Poisson regression, cluster-randomized trials, survival analysis, mediation, interactions) via simulation
  • Accounting for multiple comparisons, attrition/dropout, or clustering in the sample-size estimate

Installation

Use uv. Pin versions in production; unpinned is fine for exploration.

Read the full file on GitHub · 199 lines

Files

What ships with it

5 files 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. 3d ago First seen · 199 lines · 190 tokens per session scan A 40f9c8bd0cc9

Subscribe to this mod's changes

statistical-power is a skill published in the GitHub repository xintaofei/codeg (3,091 stars, last pushed yesterday), licensed Apache-2.0. It adds 190 tokens to every session and 3,445 once invoked, about $0.0010 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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