P-Value to Z-Score Calculator
Convert p-values to z-scores and determine critical values for statistical tests.
Calculate Z-Score from P-Value
Table of Contents
What is Z-Score?
A z-score (or standard score) is a measure that indicates how many standard deviations an element is from the mean. It is used to standardize scores and compare them across different distributions.
- Measures standard deviations from mean
- Used for standardization
- Helps compare different distributions
- Related to normal distribution
Z-Score Interpretation
|z| > 1.96
Significant at 5% level
|z| > 2.58
Significant at 1% level
|z| > 3.29
Significant at 0.1% level
|z| ≤ 1.96
Not significant at 5% level
Tail Types
Two-tailed Both Directions
Tests for differences in either direction. Used when you want to detect any significant difference, regardless of direction.
Left-tailed Lower Values
Tests for significantly lower values. Used when you want to detect if the value is significantly less than expected.
Right-tailed Higher Values
Tests for significantly higher values. Used when you want to detect if the value is significantly greater than expected.
Common Examples
Example 1 P-Value = 0.05
Two-tailed z-score = ±1.96 (borderline significant)
Example 2 P-Value = 0.01
Two-tailed z-score = ±2.58 (highly significant)
Example 3 P-Value = 0.001
Two-tailed z-score = ±3.29 (very highly significant)