Average starting hand?

[shish]

Several places on the internet, it is said that Q7off is the average starting hand. Is this true, and in what context are they referring to? For example, in the ranking of hands, is Q7 off exactly in the middle? Is there any situational considerations involved, ie. full ring vs. heads up? Is it considered the average starting hand heads up vs. a random hand? If this was already discussed, can someone please point me in the right direction, I did search but did not find anything. Thanks.