[R] Fitting weibull, exponential and lognormal distributions to left-truncated data.

[Richard.Cotton at hsl.gov.uk]

> > I have several datasets, all left-truncated at x=1, that I am 
attempting
> > to fit distributions to (lognormal, weibull and exponential).  I had
> > been using fitdistr in the MASS package as follows:

> A possible solution is to use the survreg() in the survival package 
> without specifying the covariates, i.e.
> 
> library(survival)
> survreg(Surv(..)~1, dist="weibull")
> 
> where Surv(..) accepts information about "times", censoring/truncation 
> variables and dist allows to specify alternative distributions.
> See ?Surv e ?survreg

The survival package is mostly targeted at right-censored data.  The NADA 
package provides wrappers for many of the survival routines so they work 
with left-censored data.

Regards,
Richie.

Mathematical Sciences Unit
HSL


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