multiplicity-methods

multiplicity-methods is a skill for Claude Code, Codex from choxos/BiostatAgent. It costs 30 tokens per session (2,649 once invoked), scanned A, original, MIT.

A reference for testing several clinical-trial hypotheses while controlling the chance of false-positive results. It covers methods such as Bonferroni, Holm, gatekeeping, and graphical procedures.

In plain words
What is it for?
Use it to select or implement multiplicity adjustments, gatekeeping procedures, graphical tests, and methods for controlling the family-wise error rate.
Why use it?
It helps choose a defensible way to adjust statistical tests when a trial has multiple treatment arms or outcomes.

Skill for Claude CodeCodex

Part of the clinical-trial-simulation plugin — 7 skills, 5 commands, 7 agents shipped together

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/choxos/biostatagent/multiplicity-methods
Any agent
npx skills add choxos/BiostatAgent --skill multiplicity-methods
Clone the repo
git clone --depth 1 https://github.com/choxos/BiostatAgent

Made for: Claude Code, Codex.

Or install clinical-trial-simulation, the plugin that ships this one along with the rest of its 7 skills, 5 commands, 7 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 multiplicity-methods

README.md
[![agentmods](https://agentmods.dev/badge/skills/choxos/biostatagent/multiplicity-methods.svg)](https://agentmods.dev/skills/choxos/biostatagent/multiplicity-methods)
Your own site
<a href="https://agentmods.dev/skills/choxos/biostatagent/multiplicity-methods"><img src="https://agentmods.dev/badge/skills/choxos/biostatagent/multiplicity-methods.svg" alt="Measured on agentmods" height="20"></a>
Per session 30 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,649 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 5.1 $0.00030 $0.02649
Opus 5 $0.00015 $0.01324
Sonnet 5 $0.00006 $0.00530
Haiku 4.5 $0.00003 $0.00265

Measured 5d ago against content hash 8bbf47c1820d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

multiplicity-methods 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.

plugins/clinical-trial-simulation/skills/multiplicity-methods/SKILL.md · 387 lines

How it starts

The opening of the file, as written. The whole thing — 387 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Multiplicity Methods

When to Use This Skill

  • Selecting appropriate multiplicity adjustment procedures
  • Implementing gatekeeping for primary/secondary endpoints
  • Designing graphical testing procedures
  • Optimizing truncation parameters (gamma)
  • Ensuring FWER control in multi-arm/multi-endpoint trials

Fundamental Concepts

Family-Wise Error Rate (FWER)

FWER = P(reject at least one true null hypothesis)

Multiplicity adjustments control FWER at level α (typically 0.025 one-sided or 0.05 two-sided).

Closed Testing Principle

A hypothesis H_i can be rejected at level α if and only if all intersection hypotheses containing H_i are rejected at level α.

This principle underlies most powerful multiplicity procedures.

Single-Step Procedures

Bonferroni

Method: Reject H_i if p_i ≤ α × w_i (where Σw_i = 1)

Properties:

  • Most conservative
  • Valid under any dependence
  • Simple implementation
MultAdjProc(proc = "BonferroniAdj",
            par = parameters(weight = c(0.5, 0.5)))

Step-Down Procedures

Holm Procedure

Method:

  1. Order p-values: p_(1) ≤ p_(2) ≤ ... ≤ p_(m)
  2. Reject H_(j) if p_(j) ≤ α/(m - j + 1) for all j ≤ i

Properties:

  • More powerful than Bonferroni
  • Valid under any dependence
  • Consonant and coherent
MultAdjProc(proc = "HolmAdj",
            par = parameters(weight = c(0.6, 0.4)))

Fixed-Sequence Procedure

Method: Test hypotheses in predetermined order; stop at first non-rejection.

Properties:

  • Maximum power for first hypothesis
  • Zero power for later hypotheses if early ones fail
  • Useful for clear hierarchy
MultAdjProc(proc = "FixedSeqAdj")
# Tests in order defined in AnalysisModel

Step-Up Procedures

Hochberg Procedure

Method:

  1. Order p-values: p_(1) ≤ p_(2) ≤ ... ≤ p_(m)
  2. Find largest j where p_(j) ≤ α × j/m
  3. Reject all H_(i) with p_(i) ≤ α × j/m

Properties:

  • More powerful than Holm
  • Requires positive dependence (PRDS) or independence
  • Step-up → starts from largest p-value

Read the full file on GitHub · 387 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 · 387 lines · 30 tokens per session scan A 8bbf47c1820d

Subscribe to this mod's changes

multiplicity-methods is a skill published in the GitHub repository choxos/BiostatAgent (11 stars, last pushed 3mo ago), licensed MIT. It adds 30 tokens to every session and 2,649 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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