PokerTracker

I would like to track the general looseness of tables after I've joined them.

I've tried using Table Stats and VPIP, but I'm not sure exactly how this stat works as a Table Stat. There is a Value: number which shows up on the HUD, then there is a "This Session:" stat which pops up when you hover over the table VPIP number which can be substantially different (+- 5).

What is the difference between the Value and the This Session number and how exactly is VPIP calculated as a Table Stat?

Is there a better stat for me to use as a Table Stat?

Have you added this in a "Table Averages" group?
That will show the average value of each stat for all players currently at the table, based on all of their previous hands. It's a straight average of each player's value, not weighted by their number of hands.
Tutorial: Creating a new 'Table Averages' Group

The "This Session" value only includes hands from the current table session, rather than full history.

Yes, its a "Table Averages: Show on Table" group.

Why would it have the two values 'Value:" and "This Session:" and what is the difference in how they are calculated?

Aha!

So the number I really want is the 'This Session' number, but I have to hover to get it.

Is there a way to swap the two numbers so that the This Session number is the one that is displayed?

Is there another workaround for my application of measuring table looseness at a glance?

No, you can't see the session only stat directly on the table at the moment. This has been requested before, but I don't know when it will be added.
The table average won't directly show how this table has been playing, but it will show how the current players play overall.

OK, spent the night multi-tabling and hovering on that stat.

Mark me down as one user that would find this stat a very useful one to display without the need to hover. I hope its added in an update soon.

Its obviously very useful to know how the players at the table 'usually' play, but if there are a couple of bad players that other players are trying to get into hands with, the table can suddenly get much looser. The sooner we as players (presumably multi-tabling) can adjust, the better.

The devs are aware of the request for "session" stats like average pot and VP$IP but I don't know when it will be added.

After playing a bit more using the 'This Session' stat, I've noticed a few disturbing incidents, mostly to do with the 'This Session' VPIP number fluctuating unexpectedly when used as a Table Average.

The one that stands out was when one of my FTP tables had been open for approximately 95 hands and the VPIP Table Average stat was very low, about 10/9 for Table Average/This Session. I unclicked my auto blind, intending to leave this table due to its nittiness and moved my attention to other tables. One hand later I returned to play a hand at this table and the number had jumped to 14/13.

Even if all 9 players had played that hand, I can't see how that particular 'This Session' number could jump so much

What governs the start and finish to a session for the 'This Session' stat?

I'm wondering if a new player sitting down might trigger a new session? If so, are there other triggers to a new session?

The start and finish should be based on your own play - when you sit it's a new session, when you stand up and 15 minutes have elapsed the session has ended. Please report these statistical errors so that we can investigate their causes more thoroughly.