st: Kvalseth R-squared for 0-constant or noconstant

[Bas de Goei <bas.degoei@gmail.com>]

Hmm, my searches online have provided me with some insightful work by
Kvalseth (1985). Apparently, he has an alternative R-squared which
should work across models (including no constant or 0 constant
models).

It's specified by 1 - [(Y-XBhat) ' (Y-XBhat) / Y'Y - Ymean squared]

I could put it in myself, or is there already a user-written command
for this uniform R-squared?
*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/