Template:Example: Published 2P Weibull Distribution Complete Data RRY Example

Weibull Distribution Example 15: 2-Parameter with RRY
From Dimitri Kececioglu, Reliability & Life Testing Handbook, Page 418 [20].

Sample of 10 units, all tested to failure. The times-to-failure were recorded at 16; 34; 53; 75; 93; 120; 150; 191; 240; and 339 hours.

Published Results for Weibull Distribution Example 15
Published Results (using Rank Regression on Y):



Computed Results for Weibull Distribution Example 15
This same data set can be entered into Weibull++ 7 by selecting the Times to Failure type. Use RRY for the estimation method.

Weibull++ computed parameters for RRY are:



The small difference between the published results and the ones obtained from Weibull++ is due to the difference in the median rank values between the two (in the publication, median ranks are obtained from tables to 3 decimal places, whereas in Weibull++ they are calculated and carried out up to the 15th decimal point).

You will also notice that in the examples that follow, a small difference may exist between the published results and the ones obtained from Weibull++. This can be attributed to the difference between the computer numerical precision employed by Weibull++ and the lower number of significant digits used by the original authors. In most of these publications, no information was given as to the numerical precision used.