[R] SAS or R software

[Douglas Bates]

Alexander C Cambon wrote:
> I apologize for adding this so late to the "SAS or R software " thread.
> This is a question, not a reply, but it seems to me to fit in well with
> the subject of this thread.
> 
> I would like to know anyone's experiences in the following two areas
> below.  I should add I have no experience myself in these areas:
> 
> 1) Migrating from SAS to R in the choice of statistical software used
> for FDA  reporting.
> 
>  (For example, was there more effort involved in areas of
> documentation, revision tracking,  or validation of software codes?)

This brings up a question that I have often asked but have never had 
answered.  If someone asks me if R is "validated" I usually respond "by 
whom and for what?".  There seems to be an belief that the FDA validates 
software as acceptable for use in the analysis of data for a submission 
to the FDA.  However I have never met anyone who can describe to me 
exactly what this entails.  So I can't say if R is "validated" because I 
don't know what that means.

As I understand it the FDA does not certify or validate software as 
providing "correct" or acceptable answers.  I have been told that what 
the FDA requires is that the software used to produce the results quoted 
in a submission should be auditable.  That is, the FDA must be able to 
check exactly how the numerical results were produced, should they wish 
to do so.  This can be tricky for proprietary software because typically 
the group making the submission does not have access to the source code 
so there has to be a delicate three-way negotiation on the extent to 
which the software vendor will reveal their source code.  However, 
revealing source code not a difficult issue in the open source world. 
Representatives of the FDA (or anyone else, for that matter) can read 
the source code any time they want to.  In fact they are encouraged to 
do so.

So if the standard is "auditable" I don't think you get much more 
auditable than R is.