Now that you have an initial understanding of what ICM is (that's Independent Chip Model), and how it determines your equity in the overall prize pool, how can you put this concept to your advantage?
The first thing to note is that in the end game of sit ‘n’ gos (and tourneys as well, but much less frequently used), there is often a huge gap between what is known as Chip EV (cEV) and $EV. cEV is the expected value of a given play, and if you are a cash game player, you will understand this simply as "EV". Your $EV directly correlates to the ICM, again which is the value of your chip stack and how that relates your estimated prize pool equity, assuming that one does not take skill into account.
Where this can get confusing is that there are many instances where a profitable shove (or more often a profitable call) in terms of cEV may cost you greatly in terms of $EV, which is of much greater concern to your goal of profiting.
Here are some examples:
Ignoring the effect of blinds for simplicity's sake, suppose you hold AKo and are facing a shove against AQo for 1,500 chips when on the bubble in a sit ‘n’ go. Your cEV for this call is 720, which is your expected long-term profit for calling. Obviously, that's a great spot to be in, yet depending on how the other stacks at the table are faring (and other factors we won't yet concern ourselves with), this call may or may not be correct with regards to your $EV.
Since we clearly never have full knowledge of what our opponents are holding, you will often be faced with muddier decisions and less than premium holdings with which to defend yourself. Let's look at a situation on the bubble where your $EV comes into play.
Let's say you are in a 10 man, $10 sit ‘n’ go paying out $50 for first, $30 for second, and $20 for third. There are four players left, each holding an equal stack of 2,500 with the blinds at 100/200. If the action folds to a maniac shoving any two cards on the small blind when you are on the big blind, you are forced to call with a very tight range of 66+, ATo+, A8s+, and KTs+. While this may seem crazy to play so tightly against a completely random hand, what's even crazier is that it is profitable for the small blind to be shoving so loosely!
Your inability to snap off maniacal opponents profitably may seem grim, but that's really only when you look at it from the perspective of the caller. Don't forget - if the advantage of shoving so loosely in bubble situations works for your opponents, that also must mean that when the situation is reversed and the $EV of the play matches up, you get to be the aggressor while your opponent plays the role of the victim.
When on the bubble, you really need to give extra weight on the impact of your odds of losing this hand and how it will impact your chances of hitting the first money spot. After all, if you are eliminated, your chances of winning are now zero, so the value of winning a hand when the stakes are relatively large must be compensated with a corresponding increase in overall $EV, which can change drastically from hand to hand.
Depending on the number of future money places and the pay jumps between, you may still need to be aware of your $EV even after the bubble bursts. Just know that in a winner-take-all scenario, such as heads-up play or a tourney that only pays a single spot, like a Spin & Go, you will fall back to your basic knowledge of cEV or the good old fashioned method of waiting for the right spot to get your money in.
Unfortunately, the underlying $EV calculations are just too complex for all but the most gifted math savants. However, there is still hope for you...and lots of it!
There are many great tools that exist for learning ICM play, and they tend to be very reasonably priced. A good one to start with is ICMizer, which has the ability to quickly calculate the ICM shoving and calling ranges for a wide variety of end game scenarios, as well as a quiz feature to test you on your knowledge.
While learning the ins and outs of ICM takes diligence, just spending a bit of time each day familiarizing yourself with some common situations will set you off to a good start. Even just being aware of the concept is likely to give you an edge over the non-sophisticated competition in your local live or home game.