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One-Sample Test

How Statsig uses one-sample tests to compare an experiment group's metric against a fixed reference value rather than against a control group.

One-sample tests (fixed-value test)

A one-sample test compares a single sample of data against a known or hypothesized value to determine whether there is a statistically significant difference. Unlike A/B tests that compare two groups, one-sample tests evaluate whether a single group differs from a specific benchmark, target, or historical baseline.

When to use one-sample tests

One-sample tests are useful for comparing a single group against a known value:

  • Single Group Events: When only one group can trigger certain events (for example, feature usage or error types), compare against an expected baseline.
  • Algorithm Testing: Test whether an algorithm performs better than random (for example, whether a success rate differs from 50%).

Statistical considerations

One-sample tests provide a way to make statistical inferences about whether observed data differs significantly from a hypothesized value. The test helps determine whether any observed difference is due to random variation or represents a true change in the underlying process.

Enable fixed-value baseline comparison

  1. Go to the setup page of an experiment

Experiment setup screen highlighting metrics section

  1. Click the metric name

Metric name dropdown showing configure options

  1. Select Use Fixed Baseline as Control

Fixed baseline control modal for one-sample test configuration

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