Confidence Interval (Mean)
Compute an approximate confidence interval for a population mean using a z-score (normal approximation). Enter a sample mean, standard deviation, and sample size.
Why confidence intervals?
Benefits
- Quantifies uncertainty around an estimate.
- More informative than a single point estimate.
- Great for experiments, surveys, and analytics.
Common use cases
- A/B testing metrics confidence intervals.
- Survey means (e.g. satisfaction scores).
- Operational metrics (average handling time).
Note: This uses a z-score approximation (90/95/99). For small samples or unknown variance, a t-distribution may be more appropriate.
Field guide
Mean: Sample mean $\bar{x}$.
Std Dev: Sample standard deviation $s$.
Sample size: Number of observations $n$.
Confidence: 90%, 95% or 99%.
Interval: $\bar{x} \pm z\cdot \frac{s}{\sqrt{n}}$.