What is the Z-score for a confidence interval?

A Z-score for a confidence interval represents how many standard deviations a value is from the mean and determines the interval’s width. Common Z-scores:
  • 90% confidence: 1.645
  • 95% confidence: 1.96
  • 99% confidence: 2.576

    It’s used in the formula: mean ± Z × (σ/√n).
 
The Z-score for a confidence interval is a value from the standard normal distribution that corresponds to the desired confidence level, used to calculate the margin of error for estimating a population parameter.
 
Back
Top