# Normal Distribution Analysis
Analyze data for normality (quality control, measurements).
```console
$ lawkit normal tests/fixtures/normal_data.txt
Normal Distribution Analysis Results
Dataset: tests/fixtures/normal_data.txt
Numbers analyzed: 100
Quality Level: High
Distribution Histogram:
-2.50- -1.89: ██████┃░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ 11.5%
-1.89- -1.28: █████████████████┃░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ 34.0%
...
Distribution: μ=0.02, σ=1.01, Range: [-2.89, 3.12]
1σ: 68.5%, 2σ: 95.5%, 3σ: 99.7%
```
## Sigma Coverage Check
```console
$ lawkit normal tests/fixtures/normal_data.txt -v
...
Sigma Coverage:
Within 1σ: 68.5% (expected: 68.27%)
Within 2σ: 95.5% (expected: 95.45%)
Within 3σ: 99.7% (expected: 99.73%)
```