[R] Validation of R

Frank E Harrell Jr fharrell at virginia.edu
Fri Apr 18 18:56:56 CEST 2003

On Fri, 18 Apr 2003 09:50:19 -0400
"Paul, David  A" <paulda at battelle.org> wrote:

. . . 
> Now, what would REALLY be nice is if some generous organization
> would pay a bunch of programmers to spend 2 - 3 years validating
> the algorithms in R, taking the FDA's CFR guidelines into account...
> That would truly be a service to everyone.
> Sincerely,
>   David Paul

In re-reviewing FDA guidelines there are no guidelines (either usage or validation guidelines) for statistical analysis software, only guidelines for database management software and software used in medical devices.  And the only place where SAS is mentioned is related to data archiving using SAS Version 5 transport files.  That (very problematic) format is currently preferred by FDA but experts expect that will be replaced with XML in the not-too-distant future.  
What is truly important is that data analysts check their work no matter what they are doing.

By the way, I know of an important study in which incorrect final efficacy event rates were reported to FDA and in the scientific literature, due to (what I consider) a bug that has been in SAS for 30 years: a missing value is considered to be less than any valid numeric value, so "IF x < y THEN z=1" generates z=1 when x is missing and y is not.
Frank E Harrell Jr              Prof. of Biostatistics & Statistics
Div. of Biostatistics & Epidem. Dept. of Health Evaluation Sciences
U. Virginia School of Medicine  http://hesweb1.med.virginia.edu/biostat

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