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Tolerance intervals method
Dear sir/Madam,
As we know that is only have two available methods are Assume Normal Distribution and Nonparametric from tolerance intervals module, If I have 30 samples data that using Fitted Weibull/lognormal distribution and the P-value is >0.05. How do we using Tolerance interval for Weibull and lognormal distribution?
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Re: Tolerance intervals method
Hi @SengYew : If your data are Lognormal, then the natural log of the data will be normally distributed.
1. If X is your data, calculate Y=ln(X): Y has a normal distribution.
2. Get the desired Normal Tolerance Interval for Y.
3. Back transform the interval ( exp[lower TI], exp[upper TI] ) to get the Tolerance interval back on the original X scale.
Weibull? Not so straightforward I'm afraid:
See the following: Lawless, J. F. (1975). Construction of tolerance bounds for the extreme-value and the Weibull distribution. Technometrics, 17, 255—261.
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Re: Tolerance intervals method
Hi @MRB3855,
Based on your above response I am assuming the answer is no - does JMP have integrated tools for construction of Weibull tolerance intervals per the paper you have referenced?
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Re: Tolerance intervals method
Hi @scappuccio You assume correctly; the answer is no. However, I don’t know if there are plans to add that functionality in the future.