Power T Test

{
  "alpha": 0.05,
  "asOf": "2026-10-11T08:55:57.107Z",
  "degraded": false,
  "design": "two-sample",
  "disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
  "effectSize": 0.5,
  "nPerGroup": 64,
  "notChecked": [
    "the true effect size, which is unknown before the study (use the smallest effect worth detecting)",
    "attrition, non-compliance and non-normal data",
    "…2 more"
  ],
  "power": 0.8,
  "reasons": [
    "Formula n = k (z(alpha/2) + z(power))^2 / d^2 plus z(alpha/2)^2 / (2k) as the small-sample correction (k = 2 for two groups, 1 otherwise).",
    "Plan for dropouts: divide by the expected completion rate."
  ],
  "source": "computed locally",
  "summary": "two-sample, d = 0.5, alpha 0.05, power 80%: 64 per group (128 in total).",
  "totalSubjects": 128,
  "unrounded": 63.751403,
  "verdict": "SAMPLE_SIZE",
  "zAlpha": 1.959964,
  "zBeta": 0.84162123
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://stats-tests.x402tookit.com/power-t-test?alpha=0.05&design=two-sample&effectSize=0.5&power=0.8'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - 'https://stats-tests.x402tookit.com/power-t-test?alpha=0.05&design=two-sample&effectSize=0.5&power=0.8' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode

// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

// Pays at most $0.02 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.02" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.02 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fstats-tests.x402tookit.com%2Fpower-t-test
const res = await pay("https://stats-tests.x402tookit.com/power-t-test?alpha=0.05&design=two-sample&effectSize=0.5&power=0.8");
console.log(res.status, await res.text());

# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.02 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.02"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://stats-tests.x402tookit.com/power-t-test?alpha=0.05&design=two-sample&effectSize=0.5&power=0.8")
    print(res.status_code, res.text)