How much ink is low-ink in a printer cartridge

LIfehacker points to a great PCWorld article, where the PCWorld guys hit the labs with cartridges from prominent ink jet printers (Canon, HP, Kodak, Epson). In a nutshell, They found out that

Almost all of these guys except HP stopped printing after some low ink warnings. HP continued printing (kinda like duracell) until the ink totally ran dry.
All the cartridges start giving out low ink warnings (and some even shutdown), when there is a large quantity of ink still left -- upto a whopping 45% of the original ink left! What a waste !!
They also found out that for most of these printers (except Kodak), printers reported low ink on aftermarket cartridges earlier than original cartridges.

All this is good info -- but something at the back of my mind tells me, "Hmm, did HP pay PCWorld more than the other guys did ? ". Well, obviously all of them paid PCWorld for the comment that "original cartridges are better than third party catridges". Well, well ..... Check out the article here .