MTBF(지수분포) 구간 추정의 계수표 (정시중단)

고장수 $r$ 60% 80% 90% 95%
상 하 상 하 상 하 상 하
1 4.481 0.334 9.491 0.257 19.496 0.211 39.498 0.179
2 2.426 0.467 3.761 0.376 5.628 0.318 8.257 0.277
3 1.954 0.544 2.722 0.449 3.669 0.387 4.849 0.342
4 1.742 0.595 2.293 0.500 2.928 0.437 3.670 0.391
5 1.618 0.632 2.055 0.539 2.538 0.476 3.080 0.429
6 1.537 0.661 1.904 0.570 2.296 0.507 2.725 0.459
7 1.479 0.684 1.797 0.595 2.131 0.532 2.487 0.485
8 1.435 0.703 1.718 0.616 2.010 0.554 2.316 0.508
9 1.400 0.719 1.657 0.634 1.917 0.573 2.187 0.527
10 1.372 0.733 1.607 0.649 1.843 0.59 2.085 0.544
11 1.349 0.744 1.567 0.663 1.783 0.604 2.003 0.559
12 1.329 0.755 1.533 0.675 1.733 0.617 1.935 0.572
13 1.312 0.764 1.504 0.686 1.691 0.629 1.878 0.585
14 1.297 0.772 1.478 0.696 1.654 0.640 1.829 0.596
15 1.284 0.780 1.456 0.704 1.622 0.649 1.787 0.606
16 1.272 0.787 1.437 0.713 1.594 0.658 1.750 0.616
17 1.262 0.793 1.419 0.720 1.569 0.667 1.717 0.625
18 1.253 0.799 1.404 0.727 1.547 0.674 1.687 0.633
19 1.244 0.804 1.390 0.734 1.527 0.682 1.661 0.640
20 1.237 0.809 1.377 0.740 1.509 0.688 1.637 0.647
21 1.230 0.813 1.365 0.745 1.492 0.694 1.615 0.654
22 1.223 0.818 1.354 0.750 1.477 0.700 1.596 0.660
23 1.217 0.822 1.344 0.755 1.463 0.706 1.578 0.666
24 1.211 0.825 1.335 0.760 1.450 0.711 1.561 0.672
25 1.206 0.829 1.327 0.764 1.438 0.716 1.545 0.677
26 1.201 0.832 1.319 0.768 1.427 0.721 1.531 0.682
27 1.197 0.835 1.311 0.772 1.417 0.725 1.517 0.687
28 1.193 0.838 1.304 0.776 1.407 0.729 1.505 0.692
29 1.189 0.841 1.298 0.780 1.398 0.733 1.493 0.696
30 1.185 0.844 1.291 0.783 1.389 0.737 1.482 0.700
40 1.156 0.865 1.245 0.810 1.325 0.768 1.400 0.734
50 1.137 0.879 1.214 0.829 1.283 0.790 1.347 0.759
60 1.124 0.889 1.193 0.843 1.254 0.807 1.310 0.777
70 1.113 0.898 1.176 0.854 1.232 0.820 1.283 0.791
80 1.105 0.904 1.163 0.863 1.214 0.830 1.261 0.803
90 1.098 0.910 1.153 0.870 1.200 0.839 1.244 0.814
100 1.093 0.915 1.144 0.877 1.189 0.847 1.229 0.822

단, 상하한을 구하기 위해 MTBF에 곱해야 할 계수는 $$ \left( \frac{2r}{\chi^{2}_{1-\alpha/2} (2r)} , \frac{2r}{\chi^{2}_{\alpha/2} (2(r+1))} \right) $$ 로 하여 산출