| 這張牌的放槍率Deal-in rate of this tile | 打這張的期望值Expected value | 判斷Call |
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怎麼算的How it works
期望值就是同一個決定重複做很多次，平均每次賺或賠多少。打出一張危險牌只有兩種結果：放槍，賠給對手；沒放槍，繼續聽牌，等於手上握著一張「平均值 X 元的彩券」。
棄牌當作 0：不胡也不放槍。別人自摸時，你攻或守都要付，兩邊抵掉，所以不列入。
胡牌率這樣估：你聽的牌藏在「看不到的牌」裡，也就是牌牆加三家手牌。每摸一張，中的機率是「聽的張數 ÷ 看不到的牌數」。把連摸幾次都沒中的機率乘起來，用 1 去減，就是胡牌率。計算時假設不算花牌共 136 張、最後留 16 張不摸、三家沒亮出來的手牌合計約 40 張。
這個數字只算了自己摸牌。實戰還有兩個方向相反的因素：別人放槍給你會讓胡牌率往上，別人先胡會往下，兩者部分抵消，所以把它當成總胡牌率的粗略中心值。
沒算進去的：莊家、連莊、拉莊(可以自己加進台數)、一炮多響、同時有兩家聽牌、之後幾巡還會摸到的危險牌。放槍率和對手台數都是粗估；這個工具的用處是看出「打平點離實際危險程度有多遠」，差很多時粗估就足以做對決定。
Expected value is how much you win or lose on average if you make the same decision many times. Discarding a dangerous tile has only two outcomes: you deal in and pay the opponent, or you don't, stay ready, and keep holding what amounts to a lottery ticket worth X on average.
Folding counts as 0: you neither win nor deal in. When someone else self-draws you pay whether you pushed or folded, so it cancels out and is left out.
Win rate is estimated like this: your winning tiles are somewhere among the tiles you can't see, meaning the wall plus the other three hands. Each draw hits with probability "winning tiles ÷ unseen tiles". Multiply the chances of missing on every draw and subtract from 1. The model assumes 136 tiles without flowers, 16 tiles left undrawn at the end, and about 40 concealed tiles across the other three hands.
That number counts only your own draws. Two effects pull in opposite directions at a real table: opponents discarding into your hand raises it, someone else winning first lowers it. They partly cancel, so treat it as a rough center estimate of your total win rate.
Not included: dealer bonuses and streaks (add them to your tai), multiple winners on one discard, two opponents ready at once, and the dangerous tiles you will draw on later turns. Deal-in rate and opponent's tai are guesses; the point of this tool is to show how far the break-even point sits from the real danger. When the gap is large, a rough guess is enough to make the right call.