Z分数计算器 — 公式
## How to Calculate a Z-Score
### Formula
**Z = (X - mu) / sigma**
The z-score expresses how far a data point is from the population mean in units of standard deviations. A positive z-score means the value is above the mean; a negative z-score means below. Z-scores allow comparison across different scales and distributions.
### Formula
**Z = (X - mu) / sigma**
The z-score expresses how far a data point is from the population mean in units of standard deviations. A positive z-score means the value is above the mean; a negative z-score means below. Z-scores allow comparison across different scales and distributions.
计算示例
A student scores 85 on a test where the class mean is 70 and SD is 10.
- Z = (X - mu) / sigma
- Z = (85 - 70) / 10
- Z = 15 / 10 = 1.5
- The score is 1.5 standard deviations above the mean