# Thread: Raw moments of 3-parameter Weibull distribution

1. ## Raw moments of 3-parameter Weibull distribution

Hi,
I know that the formula for computing the raw moments of 2-parameter Weibull distribution is:
Mu'n=b^n*Gamma(1+n/c), where b and c are scale and shape parameters, respectively.

However, I couldn't find any exact formula for a 3-parameter Weibull distribution. Is there any simple formula for it???

2. ## Re: Raw moments of 3-parameter Weibull distribution

First I need to make sure that the 3rd parameter you mentioned is the location parameter.

https://en.wikipedia.org/wiki/Weibul..._distributions

If that's the case, then we have the following:

Let and be two 3-parameters Weibull random variable.

Then
is a 2-parameter Weibull random variable; and

As you know raw moments

Therefore,

This is not simple or very nice, but at least this is exact and can be computed.

3. ## Re: Raw moments of 3-parameter Weibull distribution

This is exactly what I needed, although not very simple (as you mentioned)

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