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Sample Size Calculator (Survey & A/B Test)
x402
Sample Size Calculator (Survey & A/B Test) is a paid API for AI agents from math-stats.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-29).
Calculates the required sample size for a survey (given margin of error) or an A/B test (given baseline conversion rate, target lift, and statistical power).
Price / call$0.02
Success—
StatusUnknown
How this service works
Required sample size for a survey (margin of error, optional finite population) or an A/B test (baseline, lift, power).
Output
Returns the required sample size as an integer, along with the z-score used, the effective confidence level, proportion assumption, whether finite population correction was applied, the unrounded infinite-population figure, a plain-English summary, and a disclaimer. For A/B tests, returns the per-variant sample size needed to achieve the requested power and confidence.
Example use cases
Survey sample size for product feedback poll
“I'm running a customer satisfaction survey and want a 3% margin of error at 95% confidence. My customer base is about 50,000 people — how many do I need to survey?”
A/B test sizing for checkout flow experiment
“We're planning an A/B test on our checkout page. Our current conversion rate is 8% and we want to detect a lift to 10%. How many users per variant do we need at 95% confidence and 80% power?”
High-confidence political poll planning
“I need to design a political poll with a 2% margin of error and 99% confidence, expecting about 50% support for the candidate. What sample size do I need?”
Technical details
Endpoint
GEThttps://math-stats.x402tookit.com/sample-size?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need to plan a data collection effort — either a survey or a controlled experiment — and want to know how many observations are required before collecting data. It is the right choice when the user is in the design phase, not the analysis phase (for post-collection analysis, use the t-test or A/B test endpoints on this same host). Prefer this over general statistical libraries when you need a fast, no-code, API-accessible answer with finite-population correction support.
Side effects
- Missing required 'mode' parameter returns an error
- Invalid mode value (not 'survey' or 'ab') returns a validation error
- For survey mode: missing 'margin' parameter causes failure
- For ab mode: missing 'baseline' or 'target' parameters causes failure
- Out-of-range confidence (outside 0.80–0.999) returns a validation error
- Out-of-range power (outside 0.50–0.99) returns a validation error
- Baseline and target rates equal (zero lift) may return an error or infinity
- Non-positive population size returns a validation error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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