preregister

A planning document for a research study, registered with services such as OSF or AsPredicted before data collection or analysis. It records the hypotheses, sample, measures, exclusions, main analysis, and rules for handling deviations.

In plain words
What is it for?
Use it to specify research questions, sample size and stopping rules, exclusion thresholds, outcome measures, the main statistical model, robustness checks, and how changes will be reported.
Why use it?
It creates a dated record of what the researchers planned, helping distinguish planned tests from decisions made after seeing the data.

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/matthewdigiuseppe/mstack/preregister
Any agent
npx skills add matthewdigiuseppe/MStack --skill preregister
Clone the repo
git clone --depth 1 https://github.com/matthewdigiuseppe/MStack

Made for: Claude Code, Codex.

Per session 77 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,070 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 $0.00077 $0.01070
Opus 5 $0.00039 $0.00535
Sonnet 5 $0.00015 $0.00214
Haiku 4.5 $0.00008 $0.00107

Measured 2d ago against content hash 58eae3aa9336, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

preregister 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.

skills/preregister/SKILL.md · 91 lines

How it starts

The opening of the file, as written. The whole thing — 91 lines — stays where its author put it; the contents beside it link to each section on GitHub.

/mstack:preregister

Stage: design Voice: preregistration-clerk

When to invoke

Before fielding a survey, before running a secondary-data analysis on a sample you haven't touched, or before any design where you want to credibly distinguish confirmatory from exploratory analysis.

Procedure

  1. Load context.

    • .mstack/research-question.md, .mstack/lit-map.md, .mstack/identification-review-*.md.
    • .mstack/survey-design.md if a survey is involved.
    • paper/sections/theory.tex and methods.tex if drafted.
  2. Pick a registry. Default to OSF; AsPredicted if the design is small (≤ 9-section format). Note the choice in the document header.

  3. Draft prereg/osf-prereg.md — start from the bundled skeleton at ${CLAUDE_PLUGIN_ROOT}/skills/preregister/assets/prereg-template.md — with these sections, all required:

    1. Hypotheses

    List H1, H2, … with direction and effect size sign. State which is primary; secondaries are explicitly secondary.

    2. Sample

    • Population.
    • Recruitment source (Prolific, MTurk, panel name, observational frame).
    • Target N. Justification = /mstack:power-analysis output.
    • Stopping rule: time-bound, N-bound, or both.

    3. Exclusions

    List every exclusion rule with a threshold, decided before seeing data. From survey-design.md probe manifest if applicable.

    4. Measures

    • Independent variable(s) — definition, source, scale.
    • Dependent variable(s) — definition, source, scale, scoring rule.
    • Covariates — what is controlled for, why.

    5. Primary analysis

    The one specification that tests H1. State equation, sample, SE clustering, software, and the rejection rule (e.g., two-sided test at α = 0.05).

    6. Secondary analyses

    Pre-specified secondaries and any planned heterogeneity / moderation tests.

    7. Robustness

    List the robustness checks committed to in advance (e.g., alternative samples, alternative operationalizations, alternative SE structures).

Read the full file on GitHub · 91 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. 2d ago First seen · 91 lines · 77 tokens per session scan A 58eae3aa9336

Subscribe to this mod's changes

preregister is a skill published in the GitHub repository matthewdigiuseppe/MStack (14 stars, last pushed 5d ago), licensed MIT. It adds 77 tokens to every session and 1,070 once invoked, about $0.0004 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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