10 CFR Part 429, Appendix A
Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
| Degrees of freedom(from Appendix A) | Confidence Interval |
|---|---|
| 90% | 95% | 97.5% | 99% |
| 1 | 3.078 | 6.314 | 12.71 | 31.82 |
| 2 | 1.886 | 2.92 | 4.303 | 6.965 |
| 3 | 1.638 | 2.353 | 3.182 | 4.541 |
| 4 | 1.533 | 2.132 | 2.776 | 3.747 |
| 5 | 1.476 | 2.015 | 2.571 | 3.365 |
| 6 | 1.44 | 1.943 | 2.447 | 3.143 |
| 7 | 1.415 | 1.895 | 2.365 | 2.998 |
| 8 | 1.397 | 1.86 | 2.306 | 2.896 |
| 9 | 1.383 | 1.833 | 2.262 | 2.821 |
| 10 | 1.372 | 1.812 | 2.228 | 2.764 |
| 11 | 1.363 | 1.796 | 2.201 | 2.718 |
| 12 | 1.356 | 1.782 | 2.179 | 2.681 |
| 13 | 1.35 | 1.771 | 2.16 | 2.65 |
| 14 | 1.345 | 1.761 | 2.145 | 2.624 |
| 15 | 1.341 | 1.753 | 2.131 | 2.602 |
| 16 | 1.337 | 1.746 | 2.12 | 2.583 |
| 17 | 1.333 | 1.74 | 2.11 | 2.567 |
| 18 | 1.33 | 1.734 | 2.101 | 2.552 |
| 19 | 1.328 | 1.729 | 2.093 | 2.539 |
| 20 | 1.325 | 1.725 | 2.086 | 2.528 |
[76 FR 12451, Mar. 7, 2011; 76 FR 24780, May 2, 2011]