# Thoughts on Chen's formula

These days I came across this post describing the Chen's formula.

The Chen formula is a system for scoring different starting hands in Texas Hold'em. It was created by Bill Chen for use in the book Hold'em Excellence by Lou Krieger. Bill Chen is also the guy that wrote The Mathematics of Poker.

The process looks a little tricky at first, but it's really quite straightforward and logical after you have worked through a handful of examples.

I wonder: what are the pros and cons of this formula? What are it's main critiques? Do you believe that consistently following the rule is a good strategy?

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Chen's formula is limited in the way that any formula is - as said above it doesn't take account of who you're playing against. Also, though, it has major flaws in logic (why under connectedness would Ace not count as high or low? Why would you get a bonus for making a straight with community cards higher than your hole cards, but not with community lower than your hole cards - that's just asking to get beaten by a higher straight). In some ways, at least a formula gets beginners thinking about the strength of their hand, but the point of the formula is supposed to be to make things easier - yet the beginner still has to...

a) Calculate the Chen rating

b) Decide on where the line between fold & play is, taking into account...

1. position
2. number of players at the table
3. size of the blinds compared to size of stack (tournament)

I guess there's a place for a formula like this, but it needs to be better thought out - and preferably backed up by some stats.

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In the end, any formulaic starting hand strategy is going to suffer from major weaknesses due to the fact that it fails to make the proper adjustments for the specific players you are playing against. Chen's formula is no exception.

If you're just starting out, this provides as good a strategy as any for giving you a place to start. It will point you in the right direction for the vast majority of hands. The few major complaints I have with specifics of the strategy are:

1. It appears to over-value suitedness in some situations. AJs and KQs are pretty much never going to be as good as AKo. And further, playing AJs/KQs from early position at a full ring game can easily get you into a lot of trouble.
2. It leads to beginners playing marginal hands without a solid understanding of why they are playing them. Playing small suited connectors in position is very +EV, as long as you are playing them significantly differently than you would play AKo from early position. But if you do not understand the differences, you will often end up in trouble with the suited connectors.
3. Never calling a raise with hands less than a value of 10 gives up on a lot of +EV situations. Specifically (assuming that stacks are sufficiently deep), set-mining with pocket pairs and playing suited connectors in multiway pots.
4. It appears to also over-value middle pairs. This is likely to lead players to get lost with middle pairs. For instance, 77 is almost never better than AK - and that goes doubly true for beginning players. Hell, think about the reputation beginners give to JJ!
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Sorry, but what is a "+EV" situation? – Lucas Reis Jun 12 '12 at 16:01
Shorthand for "Positive expected value." Basically, a situation where you can reasonably expect the play to be profitable. – Jeffrey Blake Jun 12 '12 at 16:25
I like "The Hooks" :) JJ is one of my favorite hands. – Christopher Lates Jul 18 '12 at 17:40