probsmth
September 5th, 2008, 06:17 AM
I have to evaluate a test which did not show any failures during testing time, the individual testing times are different to each other. Thus I assessed them as "suspensions".
W++ allows calculating a 1-parameter Weibull distribution with an assumed form parameter beta at a given confidence level. I am familiar with that.
Now to my question:
I would like to calculate a Lognormal distribution with these suspended parts with an assumed log standard deviation at a CL 50%. Unfortunately W++ does not allow this and proposes using a 1-parameter Weibull. Can anyone explain me, why? :confused:
My interim solution is calculating the suspended parts with a 1-parameter Weibull (beta from experience), calculate B50 and take ln(B50) as my-log for the Lognromal distribution.
W++ allows calculating a 1-parameter Weibull distribution with an assumed form parameter beta at a given confidence level. I am familiar with that.
Now to my question:
I would like to calculate a Lognormal distribution with these suspended parts with an assumed log standard deviation at a CL 50%. Unfortunately W++ does not allow this and proposes using a 1-parameter Weibull. Can anyone explain me, why? :confused:
My interim solution is calculating the suspended parts with a 1-parameter Weibull (beta from experience), calculate B50 and take ln(B50) as my-log for the Lognromal distribution.