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Math & AlgebraGenerated accuracy model review: 2026-05-06

Confidence Interval accuracy and testing

This page documents how Calwarden builds trust for this calculator: source notes, regression-style default tests, limitations, assumptions, unit handling, rounding, and visible change history.

Formula source

  • **CI = Mean ± (Z × (s / √n))** * **Z**: Z-score corresponding to the confidence level (1.96 for 95%). * **s**: Standard Deviation. * **n**: Sample Size. * **s / √n**: Standard Error of the Mean.

Test cases

Default input regression check

Generated from the checked-in default inputs and calculate function.

Inputs

  • Sample Mean: 100
  • Sample Std Dev: 15
  • Sample Size (n): 50
  • Confidence Level: 95%

Expected outputs

  • Confidence Interval: 95.84 to 104.16
  • Margin of Error (±): 4.16

Known limitations

  • This page documents the checked-in calculator logic and does not certify results for every real-world edge case.
  • Use the result as a planning estimate unless the calculator page states a stricter purpose.

Assumptions

  • The sample size must be positive and the sample standard deviation cannot be negative.
  • This calculator uses z-scores for common confidence levels, which is most appropriate for larger samples or known-population-style approximations.
  • The interval describes uncertainty around the mean estimate, not the spread of individual observations.

Unit handling

  • Sample Mean accepts numeric values.
  • Sample Std Dev accepts numeric values.
  • Sample Size (n) accepts numeric values.
  • Confidence Level accepts one of the configured options.

Rounding rules

  • Number displays use up to 2 decimal places in the calculator UI.

Version history

1.0.0 - 2026-05-06

Generated accuracy and testing page from the current confidence-interval-calculator calculator definition.

Change log

2026-05-06

Published default regression test documentation and metadata fallbacks for Confidence Interval.

Calculator transparency

Accuracy pages are generated from checked-in calculator definitions and can be upgraded with curated review metadata over time.

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