Hi,
I am trying to use censorReg to fit an exponential model to data that
is left, right and interval censored. Here is the command that I use.
fit<-censorReg(censor(data$lower,data$upper,data$status)~1,weights=data$weight
,distribution="exponential")
For some reason, I get these warning messages:
Warning messages:
1: problems in covariance matrix computations; error code iervcv = 1
in: censorReg.mlest(Yi, censor.codesi, Xi, casewti, distribution, link,
....
2: problems in covariance matrix computations; error code iervcv = 1
in: censorReg.mlest(Yi, censor.codesi, NULL, casewti, distribution, link,
....
I next plotted the likelihood for my data under an exponential model to
see what initial value I could use in censorReg to find the m.l.e..
I wasn't sure if this was the problem but it was worth trying. It turns
out that the likelihood could be maximized so I just put in my value,
say init.val, into censorReg. This is how I did it.
fit<-censorReg(censor(data$lower,data$upper,data$status)~1,weights=data$weight
,initial=init.val,distribution="exponential")
This command doesn't do anything different from before so I am confused.
From my plot of the likelihood, I can get the m.l.e. but when I put it
into censorReg..even when I give censorReg a 'good' initial value, I still
get the same error.
Any help would be greatly appreciated.
Denise
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