[R] Simulating from a Weibull distribution

[Duncan Murdoch]

On 02/09/2014, 9:52 PM, Lucy Leigh wrote:
> Hi,
> I wish to simulate some data from a Weibull distribution. The rweibull function in R uses the parameterisation
> 
> 'with shape parameter a and scale parameter b has density given by f(x) = (a/b) (x/b)^(a-1) exp(- (x/b)^a)'.
> 
> However, it would be much more useful for me to simulate data using a different parameterisation of the
> 
> Weibull, with shape a1 and scale b1,  namely f(x) = a1*b1*x^(a1-1)exp(-b1*x^a1).
> 
> However I'm not sure how to do this, as I have only ever used the random generators that come pre-programmed in R.
> 
> Is there a package or example someone can point me to that demonstrates how to simulate data from any given distribution?

That's the same distribution, just with the parameters specified
differently.  The correspondence is

a1 = a
b1 = b^(-a)

or

a = a1
b = b1^(-1/a1)

Duncan Murdoch