Source: jeff.bridgeblogging.com
Many methods of hand evaluation abound: Law of Total Tricks (LOTT), the counter to LOTT in Lawrence-Wirgren book, Losing Trick Count (LTC), and, of course, point count.
I think all of those methods pale in comparison to Culbertson’s Rule, which I had read many, many years ago in Jeff Rubens’ great book The Secrets of Winning Bridge. Rubens defines the Rule as “your hand is worth an invitation to game (or slam) if a perfect minimum holding from partner will make it a laydown”.
What makes Culbertson’s Rule better, IMHO, than alternatives is that it gets the bidder to be thinking about integrating the play into the bidding: what cards do I need from partner (that are consistent with the auction as a whole) to make the contract I am aiming for laydown? The “perfect minimum” aspect of the Rule keeps a player from getting too ambitious: if you are counting on partner to have a perfect maximum, you will frequently be disappointed; and if are counting on partner to have a hugely imperfect minimum, you are going to miss too many good games or slams.
What brings this discussion to the blog is this hand: 
A 
AJ9632 
J9 
KJ83. You open 1 and partner raises to 2. Are you worth a game try? Culbertson’s Rule thinking might follow the lines of well, if partner holds Kxxx and Q, game should be pretty close to laydown, right? Your methods will determine how you try for game, but since a perfect minimum of 5 HCP might produce a near-laydown game, surely some sort of game try is in order.
Another example (slightly adjusted, for author license) from the same club game as the hand above. Let’s say that you are playing weak notrumps, which causes you to open 1 holding KQ84 K2 AJ5 KJ54. LHO doubles and partner raises to 2. RHO passes. Do you bid more on your balanced 17 count? Well, applying Culbertson’s rule, you “give” partner ATxxx and Q, fitting nicely with your two diamond honors. You expect a heart lead, and you can quickly see that 3NT is far from laydown. Ergo, you pass. Sure, partner might have enough for game because his auction is not inconsistent with his owning the same hand as shown above but with the A instead of the Q. But that hand is not a perfect minimum and so you should not bid on.