[R] Fwd: Potential Issue with lm.influence

[Eric Bridgeford]

How can I add attachments? The following two files were attached in the
initial message

On Tue, Apr 2, 2019 at 3:34 PM Bert Gunter <bgunter.4567 using gmail.com> wrote:

> Nothing was attached. The r-help server strips most attachments. Include
> your code inline.
>
> Also note that
>
> > 0/0
> [1] NaN
>
> so maybe something like that occurs in the course of your calculations.
> But that's just a guess, so feel free to disregard.
>
>
> Bert Gunter
>
> "The trouble with having an open mind is that people keep coming along and
> sticking things into it."
> -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
>
>
> On Tue, Apr 2, 2019 at 11:32 AM Eric Bridgeford <ericwb95 using gmail.com>
> wrote:
>
>> Hi R core team,
>>
>> I experienced the following issue with the attached data/code snippet,
>> where the studentized residual for a single observation appears to be NaN
>> given finite predictors/responses, which appears to be driven by the
>> glm.influence method in the stats package. I am curious to whether this is
>> a consequence of the specific implementation used for computing the
>> influence, which it would appear is the driving force for the NaN
>> influence
>> for the point, that I was ultimately able to trace back through the
>> lm.influence method to this specific line
>> <
>> https://github.com/SurajGupta/r-source/blob/a28e609e72ed7c47f6ddfbb86c85279a0750f0b7/src/library/stats/R/lm.influence.R#L67
>> >
>> which
>> calls C code which calls iminfl.f
>> <
>> https://github.com/SurajGupta/r-source/blob/master/src/library/stats/src/lminfl.f
>> >
>> (I
>> don't know fortran so I can't debug further). My understanding is that the
>> specific issue would have to do with the leave-one-out variance estimate
>> associated with this particular point, which it seems based on my
>> understanding should be finite given finite predictors/responses. Let me
>> know. Thanks!
>>
>> Sincerely,
>>
>> --
>> Eric Bridgeford
>> ericwb.me
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>>
>

-- 
Eric Bridgeford
ericwb.me