[R] A "rude" question

[Spencer Graves]

Hi, Paul: 

      How can I access "the package tests directory" you mentioned?  
Only one of the 52 subdirectories of "library" in my current 
installation of R 2.0.1 has a "test" folder. 

      Thanks,
      Spencer Graves    

Paul Gilbert wrote:

> One point that did not get mentioned in this discussion, and I believe 
> deserves
> much more publicity, is the impact of packages tests. The design of 
> the package
> system allows package developers to put tests in packages, and these 
> are checked
> regularly (see <http://cran.at.r-project.org/contrib/checkSummary.html>).
>
> These are intended to test the package functionality, but also give R 
> what is
> perhaps the largest test suite of any statistical software (certainly 
> the most
> quickly growing). While any single package's test will never guarantee 
> that
> the package works perfectly, the ensemble goes a long way toward ensuring
> that core R functionality behaves as intended. It seems unlikely to me 
> that any
> commercial effort will ever be able to catch up.
>
> There are several ways that tests can add to our confidence that 
> calculations can be trusted. They can
>   - check against theoretical results
>   - check against published results
>   - check against results from other software
>   - check that calculations done in different ways give the same result
>   - check that monte carlo experiments give distributions that are 
> consistent
>      with expected results
>
> Some of these are relatively time consuming to set up and check the 
> first time,
> but after that they can be automatic.
>
> If you have particular calculations with specific packages that you 
> are especially
> concerned about, I encourage you to participate by devising good tests 
> and sending
> them to the package developers. (But first check the tests they are 
> already doing
> in the package tests directory.)
>
> Paul Gilbert
>
> msck9 at mizzou.edu wrote:
>
>> Dear all, I am beginner using R. I have a question about it. When you 
>> use it,
>> since it is written by so many authors, how do you know that the
>> results are trustable?(I don't want to affend anyone, also I trust
>> people). But I think this should be a question.
>>
>> Thanks,
>> Ming
>>
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