Hi. NM algorithm with restrictions.
Best regards.
Alvaro

Weibull3.sm (49,33 KiB) scaricato 1207 volta(e).

Thanks Alvaro!

Interesting. The data's outcome can be configured to look based on the limit: beta>1 or beta<1. Which one is correct? More for me to ponder...

Norm

Wrote

Thanks Alvaro!

Interesting. The data's outcome can be configured to look based on the limit: beta>1 or beta<1. Which one is correct? More for me to ponder...

Norm

Hi Norm. You can see Weibull not as a probability distribution but a family of them. When you choose a probability distribution is because someone else says that it holds for your project because he study a lot of problems seeing which one is the"correct". Question about which model is better is about which model is preferable for your 230 units: the beta < 1 sub family or the other. This information usually is given by the units manufacturer. Hope this helps.

Best regards.
Alvaro.

Wrote

Interesting. The data's outcome can be configured to look based on the limit: beta

More I read this more confused I get:

The life cycle analysis starts with n=130 units under test for time_test=499 days.
Several units fail. What is the probability that the ith unit will fail at time T hours.
Use a Weibull probability destiny distribution function. The family of rate distribution
functions is given by T: Time to failure in days.

As it looks to me: it's an exercise from undocumented lecture, thus expressed in terms of
incomplete understanding of what's needed for expressing results.
Your explanation just says: failures were observe over 499 days observed @ T days.
The missing link seems which one of the 130 unit failed ?

Stat Treasury_8 Weibull FailureAnalysis] Copy.sm (22,83 KiB) scaricato 1031 volta(e).

Wrote

More I read this more confused I get:

... more to read to de-confuse myself.

When reading papers, if I don't see the step by step of the mathematical analysis,
reproducible steps by steps on CAS, the writer writes for the birds.

Stat Treasury_8 Weibull FailureAnalysis] Copy.sm (29,08 KiB) scaricato 1046 volta(e).

Wrote

Wrote

More I read this more confused I get:

Hi Jean. Units fails, but not dead nor disappear. They can be replaced or repaired. Norma's calculus is for planning the maintenance of the units for ensure some minimal critical number of them. For sure you can't allow only 1.47 units after 200 days, you do something for prevent that, this calculus just shows when you must to do that something.

Depending of the kind of "units", this calculus also are for not overload the workshop, have enough replacements at the warehouse, ensure the reliability of the plant, and a long etc.

Best regards.
Alvaro.

Additional reading... A pdf that was linked from a MC file using a different method to determine beta and the SMATH translated worksheet.

Norm

Interestingly, using the method to determine beta on the "chain analysis" sheet figures a beta 0.77, much less than all the methods used earlier in this forum-topic-chain.File non trovato.File non trovato.

Wrote

Additional reading... A pdf that was linked from a MC file using a different method to determine beta and the SMATH translated worksheet.

Norm

Interestingly, using the method to determine beta on the "chain analysis" sheet figures a beta 0.77, much less than all the methods used earlier in this forum-topic-chain.File non trovato.File non trovato.

The Maxima-based fit in post #9 gave a value of 0,8 which is not that far off 0,77.

Which, of course, doesn't mean anything.

Thanks Martin, It's good to have results that correlate, somewhat.

Norm

Thanks for the Widget.

It ! compensates ! for not having more advanced solver.
It looks just a working trick for some data set.
It is not the conventional Weibull survival [failure is misleading].

The Hypergeometric.Edu is much different and standard as in "R"
There is one very important stat tool: Hypergeometric with and w/o replacement
RemToDo ... was under construction a while ago.

Statistics are pure convention, the matter is to agree with preferred convention

Jean

Stat Treasury_8 Weibull [log vraisemblance] Copy.sm (23,65 KiB) scaricato 1044 volta(e).
Stat Treasury_8 Weibull FailureAnalysis] Copy.sm (29,08 KiB) scaricato 1059 volta(e).
Weibull Widgets Copy.sm (59,63 KiB) scaricato 1173 volta(e).
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