[R] Testing for scale e mu in survreg

[Ronaldo Reis Jr.]

Hi,

Normally I make survival analysis using survreg in survival package.

It is simple to compare curves for different levels. But in this case all 
curves have the same estimated scale parameter.

In some cases, curves are graphically different in your behaviour.
One curve is like type I curve (1/scale > 1).
Other curve is like type III curve (1/scale < 1).
All graphics made normal and with y log scale to compare.

If I make an analysis separate for each factor, I can get obtain different 
scale parameters, but is not possible to compare the mean time for death of 
this two curves with different scales.

Existe any mean to make a survival model in R that test difference of scale 
for and difference of mean time for dead for factors?

Or I'm crazy for think in this?

Thanks
Ronaldo
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