Table of percentiles for Distribution ID Plot (Right Censoring)

The percentiles provide the age by which a percentage of the population is expected to fail.

Sometimes it may be difficult to determine the best distribution based on the probability plot and goodness-of-fit measures. Use the table of percentiles to compare the percentiles for several selected distributions to see how your conclusions change depending on the distribution chosen.

If several distributions provide a reasonable fit to the data and similar conclusions, then the choice of the distribution is less important.

However, if your conclusions differ depending on the distribution, you may want to report the most conservative conclusion, collect more data, or use additional information, such as process knowledge and expert advice.

Example output

Table of Percentiles Standard 95% Normal CI Distribution Percent Percentile Error Lower Upper Weibull 1 10.0765 2.78453 5.86263 17.3193 Lognormal 1 19.3281 2.83750 14.4953 25.7722 Exponential 1 0.809731 0.133119 0.586684 1.11758 Normal 1 -0.549323 8.37183 -16.9578 15.8592 Weibull 5 20.3592 3.79130 14.1335 29.3273 Lognormal 5 26.9212 3.02621 21.5978 33.5566 Exponential 5 4.13258 0.679391 2.99422 5.70371 Normal 5 18.2289 6.40367 5.67790 30.7798 Weibull 10 27.7750 4.11994 20.7680 37.1463 Lognormal 10 32.1225 3.09409 26.5962 38.7970 Exponential 10 8.48864 1.39552 6.15037 11.7159 Normal 10 28.2394 5.48103 17.4968 38.9820 Weibull 50 62.6158 4.62515 54.1763 72.3700 Lognormal 50 59.8995 4.31085 52.0192 68.9735 Exponential 50 55.8452 9.18089 40.4622 77.0766 Normal 50 63.5518 4.06944 55.5759 71.5278

Interpretation

Based on a lognormal distribution fitted to the engine windings data, 1% of engine windings are expected to fail by 19.3281 hours.

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