Stack-to-pot ratio

SPR = effective stack / pot. Low SPR (like 1–3) means you're often committed with strong top pair+/strong draws. High SPR means you can still fold some strong-but-second-best hands later.

Your buddy gets it in on flop with weak equity because 'the pot is big' without noticing SPR. Teach him to look at stacks behind.

Example: pot $30 after flop open, effective $90 behind → SPR = 3. Many strong hands become commit-or-fold. Compare to pot $30 with $300 behind → SPR = 10, you still have room to make disciplined folds later.