Hand deduction is something I am very bad at - actually narrowing my opponents range, based on the action. I would guess that most winning players have become reasonably adept at this?

Those of you who multi-table and are fairly good at narrowing the opponents range, by process of elimination, you obviously have to work this out fairly quickly.

Do you have a set mental routine for doing this? Do you run through all likely hands villain holds and then tick the ones he doesn't off in a certain order. Or have you just become so used to doing it that you don't need to think things through in a specific order?

How often do you find that your opponent shows up with a hand outside the range that you put him on?

The way I teach this is to go through hand histories with a replayer, with all hole cards hidden. At each action in the hand I ask the student to refine his idea of his opponent's hand range. I may help out in a few places if he is way way off. At the end of the hand, I reveal all hole cards. Then we go back and play through it again (faster) with the cards displayed.

Actions in a hand imply motivations, a desire to make something happen (well, usually). A problem is that they usually imply more than one motivation at the same time - a bet can be a desire to get a fold, or a desire to get a call. It's important to combine all the actions together to see if you can come up with a consistent set of motivations that match the hands an opponent can have.

You can do the above yourself, go through old hand histories with all the cards hidden and see if you can figure it out. It's even better if you weren't involved in the hand.

Also while playing, but not in a hand, you can watch the other players and try to see if you can tell what they have, based on how they act. It's way easier if you don't have cards.

Preflop, ranges can be pretty wide. I practice with pokerstove during my reviews so I can estimate what a 20/15 looks like vs. a 40/5.

After the flop is where I really start to narrow an opponents hand range. For example, If I hold A9 on the button, I open, and the BB calls, I can put him on a wider range than usual since I'm in a stealing position. Any ace other than AK and AQ, any pair other than AA-JJ, suited connectors down to 56, unsuited down to JT, etc. (I'm assuming he would reraise AK-AJ, KQs, AA-JJ)

So lets say the flop comes AT2

The BB checks

I can't narrow his range. If I had some reads on his lead criteria, I might be able to deduce something.

You bet 3/4 pot, and he calls.

You probably have the best hand. He's calling with way worse in his range. You have all aces in his range beat other than AT and A2. You are ahead of KT, QT, and JT. However, this call only really narrows his range slightly.

Turn K

The BB leads out with a pot bet.

Now things get tricky. What hands would he do this with? Lets say we check his stats and see his aggression freq. at 1.0. Odd play to lead out with that stat. KT would make this play, so would AT, A2, Axcc, QTcc, JTcc, TT, and 22. But let's say a few orbits ago, you remember the villain slowplayed his monster on a wet board (and he doesn't seem all that great of a player). With this the case, we can include a few of the best hands from his flop range as well. If we do the math...

AT, A2, KT, Axcc, QTcc, KJcc, JTcc, TT, 22 = 31 hands (27 that crush us)

Since he made a pot bet, how often do we have to be good here? Pot bet is 2:1 odds which means we have to be right 33%. In order for that to occur, 27 hands that don't have us crushed that we had bet against for value on the flop need to be included in his turn range. Is this reasonable? That's roughly 13 combos (we need 2:1 ratio of crushed hands to beat hands) or roughly 1.5 Ax hands. I think this is reasonable so I call.

River is a Q and the BB leads for 1/2 pot

Bad card for you. Again, looking at the math

Crush us:
Axcc, JTcc, KJcc = 11 hands

KT, QT, AT, A2 = 30 hands

22, TT = 6 hands

Total: 47 hands.

How often do we have to be right? 1/2 pot bet gives us 3:1 odds so we need to be right 25%. Vs 47 hands that have us crushed, we need villain to make his play with 16 bad hands (or 2 Ax hands). Is he still going to play a weak ace in this way, with this board? Second pair with a good kicker? Maybe, and we only need him to play two weak ace hands to make this call, or one Ax hand and 12% bluffing freq. It's a marginal call in my mind. The question is, will he make the play with enough bad hands to make the call +ev?

Some of my hand combos may be double counted (I'm doing this at work), but this is roughly my thought process through a hand. As you can see, I only count hands that have me crushed that are in my opponents pf range, then figure out how often I need to be right, and then how many more hands I beat that need to be included in my opponents crush me range to make the call profitable. If he is more likely to over value some hands, this may make the play even more +ev. If I have some decent equity in the hand (draw to the nuts), and my opponent folds too much, I may reraise him as a semi bluff on the turn, and balance this at times when I have my opponents range crushed.

Thats brilliant bjw181, thanks. Can you recommend any ebooks or good youtube videos that you would recommend, on this?

Ed Millers book on hand reading is great