Notice
You are now leaving support.minitab.com.
Click Continue to proceed to:
With a nonparametric estimation procedure, the value of the mean cumulative difference function changes only when a failure occurs.
| Mean Cumulative Difference Function | ||||
|---|---|---|---|---|
| Standard Error | 95% Normal CI | |||
| Time | Lower | Upper | ||
| 19 | -0.06667 | 0.064406 | -0.19290 | 0.05957 |
| 22 | -0.13333 | 0.087771 | -0.30536 | 0.03869 |
| 33 | -0.06190 | 0.111541 | -0.28052 | 0.15671 |
| 39 | -0.12857 | 0.124114 | -0.37183 | 0.11469 |
| 54 | -0.19524 | 0.133322 | -0.45654 | 0.06607 |
| 61 | -0.26190 | 0.139830 | -0.53597 | 0.01216 |
| 88 | -0.19048 | 0.153496 | -0.49132 | 0.11037 |
| 91 | -0.25714 | 0.183399 | -0.61660 | 0.10231 |
| 93 | -0.32381 | 0.185008 | -0.68642 | 0.03880 |
| 119 | -0.39048 | 0.228047 | -0.83744 | 0.05649 |
| 148 | -0.45714 | 0.279427 | -1.00481 | 0.09052 |
| 173 | -0.52381 | 0.277299 | -1.06730 | 0.01969 |
| 185 | -0.59048 | 0.289837 | -1.15855 | -0.02241 |
| 187 | -0.65714 | 0.285719 | -1.21714 | -0.09714 |
| 192 | -0.72381 | 0.280486 | -1.27355 | -0.17407 |
| 194 | -0.79048 | 0.274074 | -1.32765 | -0.25330 |
| 203 | -0.85714 | 0.266399 | -1.37928 | -0.33501 |
| 205 | -0.92381 | 0.274074 | -1.46099 | -0.38663 |
| 211 | -0.99048 | 0.280486 | -1.54022 | -0.44073 |
| 242 | -1.05714 | 0.285719 | -1.61714 | -0.49714 |
| 250 | -1.05238 | 0.279994 | -1.60116 | -0.50360 |
| 264 | -1.11905 | 0.298435 | -1.70397 | -0.53413 |
| 272 | -1.04762 | 0.302679 | -1.64086 | -0.45438 |
| 277 | -1.11429 | 0.318886 | -1.73929 | -0.48928 |
| 287 | -1.04286 | 0.321731 | -1.67344 | -0.41228 |
| 293 | -1.10952 | 0.308568 | -1.71431 | -0.50474 |
| 302 | -1.03810 | 0.310335 | -1.64634 | -0.42985 |
| 306 | -1.10476 | 0.350677 | -1.79208 | -0.41745 |
| 317 | -1.03333 | 0.351196 | -1.72166 | -0.34500 |
| 364 | -0.96190 | 0.350677 | -1.64922 | -0.27459 |
| 367 | -0.89048 | 0.349114 | -1.57473 | -0.20622 |
| 369 | -0.95714 | 0.335260 | -1.61424 | -0.30004 |
| 373 | -1.02381 | 0.359155 | -1.72774 | -0.31988 |
| 382 | -1.09048 | 0.343985 | -1.76467 | -0.41628 |
| 391 | -1.01905 | 0.355960 | -1.71672 | -0.32138 |
| 402 | -0.94762 | 0.352358 | -1.63823 | -0.25701 |
| 415 | -1.01429 | 0.373582 | -1.74649 | -0.28208 |
| 416 | -1.08571 | 0.371724 | -1.81428 | -0.35715 |
| 419 | -1.23956 | 0.379800 | -1.98395 | -0.49517 |
| 421 | -1.16813 | 0.388808 | -1.93018 | -0.40608 |
| 431 | -1.09670 | 0.383618 | -1.84858 | -0.34482 |
| 432 | -1.18761 | 0.381917 | -1.93616 | -0.43907 |
| 434 | -1.28761 | 0.379729 | -2.03187 | -0.54336 |
| 441 | -1.39872 | 0.376828 | -2.13729 | -0.66015 |
| 444 | -1.32729 | 0.384013 | -2.07995 | -0.57464 |
| 447 | -1.45229 | 0.380094 | -2.19726 | -0.70733 |
| 448 | -1.73801 | 0.360677 | -2.44492 | -1.03109 |
| 460 | -1.93801 | 0.345574 | -2.61532 | -1.26070 |
| 461 | -2.18801 | 0.482663 | -3.13401 | -1.24201 |
| 462 | -2.11658 | 0.476966 | -3.05142 | -1.18174 |
| 464 | -2.44991 | 0.535496 | -3.49947 | -1.40036 |
| 481 | -2.37849 | 0.529680 | -3.41664 | -1.34033 |
| 498 | -2.30706 | 0.532767 | -3.35126 | -1.26285 |
| 500 | -2.16420 | 0.546276 | -3.23488 | -1.09352 |
| 503 | -2.66420 | 0.568698 | -3.77883 | -1.54957 |
| 511 | -3.66420 | 0.568698 | -4.77883 | -2.54957 |
| 548 | -3.59277 | 0.578546 | -4.72670 | -2.45884 |
| 552 | -3.52134 | 0.587608 | -4.67303 | -2.36965 |
| 625 | -3.44991 | 0.604423 | -4.63456 | -2.26527 |
| 635 | -3.37849 | 0.595004 | -4.54467 | -2.21230 |
| 650 | -3.30706 | 0.593471 | -4.47024 | -2.14387 |
| 657 | -3.23563 | 0.599884 | -4.41138 | -2.05988 |
| 687 | -3.08178 | 0.595533 | -4.24900 | -1.91456 |
| 700 | -2.99087 | 0.592914 | -4.15296 | -1.82878 |
| 708 | -2.89087 | 0.601644 | -4.07007 | -1.71167 |
| 710 | -2.55754 | 0.586803 | -3.70765 | -1.40743 |
| 719 | -2.39087 | 0.638098 | -3.64152 | -1.14022 |
| 724 | -1.79087 | 0.674662 | -3.11319 | -0.46856 |
| 730 | -0.79087 | 0.674662 | -2.11319 | 0.53144 |
For the brake reliability data, the mean cumulative difference function is −0.99048 at 211 days. That is, the average number of repairs needed for a single system by 211 days is nearly 1 more for the type 2 brake component than for the type 1 brake component. The engineer can be 95% confident that this difference falls within the interval of −1.54022 and −0.44073.
For these data, all systems were retired for the type 2 brake component at 511 days and for the type 1 brake component at 730 days. At 511 days, the difference between the average number of repairs on each system for the two types of brake components is −3.66420. The engineer can be 95% confident that the true difference in the average number of repairs falls within the interval of −4.77883 and −2.54957. Because the confidence interval does not contain 0, a significant difference exists between the two types of brake components in the average number of repairs that are needed by the time all the systems have retired for the type 2 component at 511 days.
You are now leaving support.minitab.com.
Click Continue to proceed to: