How tight is tight?

[xniNja]

Most topics involve discussion of whether or not the Hero, villain, and table was "tight" or "loose."

Although everyone who plays poker generally has a good idea of what is meant by "tight" or "loose" players and games, I'm surprised I've never really seen it talked about in percentages.

Thus, the creation of this thread.

Questions: (based on PT and GT+ observations)
1) How "tight" do you play? (VP$IP) ::
I play about ~18-19% overall, around 10-15% on any given session if not catching any cards.

2) How "tight" are the games you play in? ::
Tightest games are about 17-18% and loosest ~27%

3) PT default rates <19% as "tight" and ~>20% as "Semi-Loose" .. where do you think these lines should be drawn, or is there any evidence that suggests which are more profitable?