[R] Cannot create summary of old glm object. How to ensure that R objects will be usable in the future.

[Prof Brian Ripley]

On 09/09/2013 08:48, Clara wrote:
> Hi all,
>
> I have an older, probably about 2 years old glm object, I am not sure
> with which version of glm it was produced. I have tried to

Before R 3.0.0, which was a change in major version number.

> summary(my.model) but I get an error.
>
>  > summary(my.model)
> Error in .Call("binomial_dev_resids", y, mu, wt, PACKAGE = "stats") :
>    "binomial_dev_resids" not available for .Call() for package "stats"
>
> Some info about the model:
> Call:  glm(formula = my.formula, family = binomial, data = my.data,
> weights = my.weights,
>      x = T, y = T)
>
> My current r version and platform:
> R version 3.0.1 (2013-05-16) -- "Good Sport"
> Platform: x86_64-pc-linux-gnu (64-bit)
>
> I have used my.model before, about a year ago, without any problems. So
> my questions are,
> (1) Is there a way to "update" the model so it works with the new
> version of summary.glm? or is there a way to make the new summary.glm
> function agreeable to my.model?

It is not to do with summary.glm: it is AFAIK due to what is stored in 
'my.model'.  You should re-fit my.model.

In this particular case (which is not reproducible to us) it is possible 
that

my.model$family <- binomial()

would work.

> (2) Should I expect this behavior with other older models? I mean, If I
> create a model today should I expect to have problems when I try to do
> simple stuff with it, like "summary", in a couple of years?

Yes.

> (3) Is there a way to prevent this? What would be the best way to make
> sure, as much as possible, that the models I produce today will be
> usable in the future by me and others?

Not save .RData files and expect them to work with an R with an 
increased major version number.

You should regard .RData files as a permanent form of storage only for 
data (things like data frames).

> Any help is greatly appreciated. I will run into this problem again, so
> I would very much appreciate any help on how to handle this.

Use the version of R you used to create the object my.model to explore it.

And BTW R 3.0.x has been out for several months and I have not seen 
anyone one else reporting such a problem so I think it is much rarer 
than you believe.

> Clara


-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595