check JJ in BB 1/2 Stars

[garion888]

Ran some numbers with Pokerstove to give a little more concrete answer.

Jacks versus 4 completely random hands...

Hand 1: 40.2881 % [ 00.40 00.00 ] { JJ }
Hand 2: 14.9383 % [ 00.14 00.01 ] { random }
Hand 3: 14.9376 % [ 00.14 00.01 ] { random }
Hand 4: 14.9188 % [ 00.14 00.01 ] { random }
Hand 5: 14.9171 % [ 00.14 00.01 ] { random }

And Jacks versus 3 randoms and a Broadway or Big Pair

Hand 1: 33.3068 % [ 00.33 00.00 ] { JJ }
Hand 2: 25.1812 % [ 00.24 00.01 ] { AA-TT, AKs-ATs, KQs-KTs, QJs-QTs, JTs, AKo-ATo, KQo-KTo, QJo-QTo, JTo }
Hand 3: 13.8504 % [ 00.13 00.01 ] { random }
Hand 4: 13.8251 % [ 00.13 00.01 ] { random }
Hand 5: 13.8364 % [ 00.13 00.01 ] { random }

I think it's to estimate your equity pre-flop at around 35%. You are going to win much more than your fair share of 20% of the time versus 4 people, therefore you raise. Simple as that. As the number of opponents goes down, your equity obviously improves.

Hope this helps...
-j