Re: st: generate variable versus define scalar, with conditional statement

[Nick Cox <njcoxstata@gmail.com>]

The code here uses the mean for -newscalar- if and only if there is
just one value, in which case the mean is just that one value.

Everything depends on what the code is trying to do, but in many cases
where I am summarizing data I am happy to use a constant as summary
when the data are indeed constant. Hence

        if r(min) == r(max) scalar newscalar = r(mean)

This criterion necessarily is consistent with r(N) == 1.

On Thu, Jan 17, 2013 at 10:02 AM, Seed, Paul <paul.seed@kcl.ac.uk> wrote:
> Just realised I had a typo:
> It should be r(N), not r(n).
>
> The correct version is:
>
>         clear all
>         sysuse sp500
>
>         summ  open if date == mdy(1,2,2001), meanonly
>  /// the meanonly option suppresses output, and saves computer time
>  ///by not calculating the standard deviation.  It is not essential.
>         scalar newscalar_mean = r(mean)
>         scalar newscalar_min= r(min)
>         scalar newscalar_max= r(max)
>         if r(N) == 1 scalar newscalar = r(mean)
>         else scalar newscalar = .
*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/faqs/resources/statalist-faq/
*   http://www.ats.ucla.edu/stat/stata/