All you seek can be found at http://www.weldreality.com, including references (offered for sale) covering the subject in depth. Give yourself several hours to thoroughly peruse the wealth of information provided.
You will know by looking into the arc at the actual transfer going on, the sound, the lack of spatter, high deposition rate and the fluid weld bead characteristics...
...but I believe John's different answer was indeed the (W)right one to answer the point of your question, no?
(you may need a bit darker shade for your shield lense to actually see the arc detail if it gives you difficulty)
Regards,
d