[Rd] Covergence FLAG in glm (PR#7235)

maechler at stat.math.ethz.ch maechler at stat.math.ethz.ch
Sat Sep 18 16:54:48 CEST 2004

>>>>> "daniel" == daniel jeske <daniel.jeske at ucr.edu>
>>>>>     on Sat, 18 Sep 2004 04:10:40 +0200 (CEST) writes:

    daniel> Full_Name: Daniel R Jeske Version: 1.8.1 OS: Windows
    daniel> 2000 Submission from: (NULL) (

    daniel> We have just noticed that when you use glm() it
    daniel> seems the logical output 'converged' is always TRUE.
    daniel> The same data set that shows FALSE in version 1.7.1
    daniel> shows TRUE in 1.8.1.  And I know that FALSE is the
    daniel> correct answer...so it seems like we cannot trust
    daniel> the 'converged' flag for glm() in version 1.8.1
    daniel> ?????

I'm pretty sure you're wrong:

The  NEWS  file for 1.8.0  contains

>>    o	   The defaults for glm.control(epsilon=1e-8, maxit=25) have been
>>         tightened: this will produce more accurate results, slightly slower.

Hence, compared to 1.7.1, glm() in your (still very outdated!!)
version 1.8.1 will by default use more iterations and may well
converge in cases it didn't in 1.7.1 

If there weren't such cases, the change wouldn't have been


Note that even if you were right, your bug report would be
basically unusable as bug report and we ask to   
PLEASE only send bug reports (to R-bugs at ... that is) if you know
how to do it -- i.e. if you have read that section in the R FAQ.

Martin Maechler

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