power-analysis-guide

power-analysis-guide is a skill for Claude Code, Codex from wentorai/research-plugins. It costs 12 tokens per session (2,080 once invoked), scanned A, original, MIT.

A guide to power analysis, a method for calculating how many observations a study needs. It explains how sample size, expected effect, false-positive risk, and the chance of detecting a real effect are related.

In plain words
What is it for?
Use it to plan sample sizes, choose or interpret effect sizes, understand statistical power, and assess Type I and Type II errors in study designs.
Why use it?
It helps avoid studies that are too small to detect meaningful effects or unnecessarily large for the question being studied.

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/wentorai/research-plugins/power-analysis-guide
Any agent
npx skills add wentorai/research-plugins --skill power-analysis-guide
Clone the repo
git clone --depth 1 https://github.com/wentorai/research-plugins

Made for: Claude Code, Codex.

Wrote this? Show the measurements

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agentmods badge for power-analysis-guide

README.md
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Per session 12 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,080 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 $0.00012 $0.02080
Opus 5 $0.00006 $0.01040
Sonnet 5 $0.00002 $0.00416
Haiku 4.5 $0.00001 $0.00208

Measured 5d ago against content hash 08e82ea6f244, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

power-analysis-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 5d 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/statistics/power-analysis-guide/SKILL.md · 241 lines

How it starts

The opening of the file, as written. The whole thing — 241 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Power Analysis Guide

Calculate appropriate sample sizes for your study using power analysis, understand effect sizes, and avoid underpowered or wastefully overpowered designs.

Core Concepts

The Four Parameters of Power Analysis

Every power analysis involves four interrelated quantities. Fix any three to solve for the fourth:

Parameter Symbol Definition Typical Value
Effect size d, r, f, etc. Magnitude of the phenomenon you expect to detect Varies by field
Significance level (alpha) alpha Probability of Type I error (false positive) 0.05
Statistical power (1 - beta) 1 - beta Probability of detecting a true effect 0.80 or 0.90
Sample size N Number of observations needed Solve for this

Error Types

H0 is true (no effect) H0 is false (effect exists)
Reject H0 Type I error (alpha) Correct (power = 1 - beta)
Fail to reject H0 Correct (1 - alpha) Type II error (beta)

Effect Size Conventions

Cohen's d (Two-Group Comparison)

d = (M1 - M2) / SD_pooled
Size Cohen's d Interpretation
Small 0.2 Subtle, may need large N to detect
Medium 0.5 Noticeable, typical in social sciences
Large 0.8 Obvious, often visible without statistics

Correlation (r)

Size r r-squared
Small 0.1 1% variance explained
Medium 0.3 9% variance explained
Large 0.5 25% variance explained

Cohen's f (ANOVA)

Size f Equivalent eta-squared
Small 0.10 0.01
Medium 0.25 0.06
Large 0.40 0.14

Odds Ratio (Logistic Regression)

Size OR
Small 1.5
Medium 2.5
Large 4.0

Power Analysis in Python (statsmodels)

Two-Sample t-Test

from statsmodels.stats.power import TTestIndPower

analysis = TTestIndPower()

# Solve for sample size
n = analysis.solve_power(
    effect_size=0.5,    # Cohen's d = medium
    alpha=0.05,         # Significance level
    power=0.80,         # 80% power
    ratio=1.0,          # Equal group sizes
    alternative='two-sided'
)
print(f"Required N per group: {int(n) + 1}")  # Output: 64

# Solve for power (given N)
power = analysis.solve_power(
    effect_size=0.5,
    alpha=0.05,
    nobs1=50,
    ratio=1.0,
    alternative='two-sided'
)
print(f"Power with N=50 per group: {power:.3f}")  # Output: 0.697

Read the full file on GitHub · 241 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. 5d ago First seen · 241 lines · 12 tokens per session scan A 08e82ea6f244

Subscribe to this mod's changes

power-analysis-guide is a skill published in the GitHub repository wentorai/research-plugins (287 stars, last pushed 2mo ago), licensed MIT. It adds 12 tokens to every session and 2,080 once invoked, about $0.0001 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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