If its you have you checked your release or bow arm position are the 2 that I have problems with that cause me to have a bad group.

Weak arrows will fly right. stiff arrows will fly left. Only way to tell is bareshaft tuning. (rh shooter)

If its you, move way up. start 2 yds from target. move back slowly over time.

don’t despair, keep at it. It happens to everyone. It can be the best learning tool. Nobody ever learned anything from getting it right.

Its probably you. With two exceptions even mistuned arrows will group. As stated before, assuming RH shooter, weak to the right, stiff to the left, but they will none the less group in those orientations. The exceptions are 1) arrow sooooo stiff the nock end strikes the riser as it passes by. This will give a rough false weak indication, but grouping will be practically nonexistant. 2) Nock slide, on release the nock slides down the string a short ways, 1/8″ to 1/4″. It can be fixed by the addition of a second nock set below the arrow nock.
It may or may not be happening to you, but it REALLY can happen, check these videos:
http://picasaweb.google.com/116451859615119061133/AVIs?gsessionid=ScCvML4LRT38un6vxWqdmg#
If nock slide happens you will get a rough indication of a nock height problem, usually showing nock high because the nock end hits the shelf and bounces up. But again grouping will be nonexistant.

Great videos. They show what you could never see just watching. thanks, d