Template:Example: Published 2P Weibull Distribution Interval Data MLE Example

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Published 2P Weibull Distribution Interval Data MLE Example

From Wayne Nelson, Applied Life Data Analysis, Page 415 [30]. One hundred and sixty-seven (167) identical parts were inspected for cracks. The following is a table of their last inspection times and times-to-failure:

Example16table.png


Published Results:

Published results (using MLE):

Example16formula.png

Published 95% FM confidence limits on the parameters:

Example16formula2.png

Published variance/covariance matrix:

Example16formula3.png


Computed Results in Weibull++

This same data set can be entered into Weibull++ by selecting the data sheet Times to Failure, with Right Censored Data (Suspensions), with Interval and Left Censored Data and with Grouped Observations options, and using MLE.

Weibull++ computed parameters for maximum likelihood are:

Compexample16formula.png

Weibull++ computed 95% FM confidence limits on the parameters:

Compexample16formula2.png

Weibull++ computed/variance covariance matrix:

Compexample16formula3.png