Hi Artur/Sven

 checked Help Add Ons(at the very bottom of the list of items).-

All that appeared was this.

There was no mention of the k means package.  However, I thought it worth a try downloading the package again. Lo and behold it loaded and attached to the GUI. So thanks for your help whcih led to a solution, though the logic of this process still seems obscure. Had kmeans been listed in the Addon it might have been clearer why.

No - kmeans is a contributed package and does not have "addon" status, so it would never appear in that window. I understand that the distinction between official addons and contributed packages can be confusing, but it exists.

Actually, maybe the "gretl: addons" window should contain a short remark that there are also other packages besides the addons (and how to look for them). And to be honest, it's not quite clear why the entry "Look for addons" is under the Help menu in the first place. It might be more logical to put them under the File menu (where the contributed packages are), or under Tools.

cheers

sven