Life Distribution with defective subpopulation<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />Hi,
Attached there is an data set from a customer with defective subpopulations. He uses life distribution, and wants to fit a DS Weibull distribution as Weibull does not a good job because of defective subpopulation.
The issue is that with the original data DS Weibull shows a fit, but no confidence interval and the message says “Failure: Cannot decrease objective function” and “Convergence failed: Cannot decrease objective function”. After creating a new column with a log10 transformation of the time data I am able to fit a DS Weibull.
Can someone explain to me why this is the case (both I cannot see the confidence intervals and why there is a difference if log transformed or not)?
The customer is Robert Bosch and the data is confidential. But Bosch could become a good opportunity in case the evaluation works out.
Thanks,
Martin
Re: Life Distribution with defective subpopulationThanks, Malcolm, this helped a lot and explains the difference to the log transformed, as there the Zero value turned into a(n) (undefied) missing value. Therefore this row is not used in the Analysis and works as expected.
Martin
Re: Life Distribution with defective subpopulationTry excluding and hiding row 1 Martin which seems to be a censored observation at time zero. DS Weibull seems to fit ok if you exclude this point and I'm not sure of the logic of a censored observation at time zero!
