CODEWITHSUNDEEP
rsurvival-analysisweibull
Zephyr
Zephyr

Reputation: 138

R Survival Analysis: error in survreg using Weibull

I'm trying to replicate some survival analysis using the Weibull distribution that I have previously produced in SAS - I'm now working from an unlicensed machine so am using R (both from Windows). My (right censored) input data looks like:

> head(mydata)
  ID         Key  Time  Score    Event    Censor
1 1231231    ZXC   28   182.34   0      1
2 4564564    ASD   28   320.04   0      1
3 7897897    QWE   28   306.32   0      1
4 9879879    QWE   28   211.92   0      1
5 6546546    ASD   28   276.14   0      1
6 3213213    ZXC   28   331.50   0      1

with Event and Censor being binaries, Score varying between about 150 and 450 and Time between 1 and 28. There are some 30,000 rows in the input dataset.

When I try:

mydatasr <- survreg(Surv(Time, Censor) ~ Score, dist = "w")

I get a warning message:

In survreg.fit(X, Y, weights, offset, init = init, controlvals = control, : Ran out of iterations and did not converge,

And no output.

I've searched for this msg online (and through this site) but have not managed to find anything that indicates what the problem might be. I had no convergence issues putting the same data through (proc logistic and) lifereg in SAS.

Upvotes: 2

Views: 4264

Answers (2)

IRTFM
IRTFM

Reputation: 263342

It's difficult to know in the absence of data. You can double (or as illustrated below, triple) the number of iterations which defaults to 30:

(mydatasr <- survreg(Surv(Time, Censor) ~ Score , dist = "w", control = list(maxiter=90) )

See ?survreg.control for further options. I also am guessing you may have missed that a Surv-object has a closing parenthesis before the formula-~

Upvotes: 3

Yong
Yong

Reputation: 1127

Try this:

   survreg(Surv(Time, Censor) ~ Score, data=mydata, dist = "w", scale=1)

Upvotes: 0

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