Spencer Graves wrote:
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.
The tests directory seems to get stripped when you install a package. If you get a source package and untar it then there will be a tests directory in many packages (it is not required).
Paul
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
[EMAIL PROTECTED] 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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