Using Odds During a Bluff
It's always good to look at poker from a mathematical perspective, and that even applies to bluffing. You can determine finite amounts and percentages that can tell you if it is a financially feasibly good time to bluff. This is particularly useful when there are only one or two players and the pot is rather large.
It's good to do these calculations with potential straights or flushes that appeared on the river, that you were going for but you didn't make. It's nice with a flop that starts with Heart, Heart, Spade, and ends with Spade, Spade. You had two Hearts. Or a flop like Five, Seven, Eight, and ends with Ten, Jack. You had a Six. It's also good because they might have been on the same draw, which leads them to believe (also from on odds perspective) that you were not on that draw.
Let's say that one of the above cases occurred in a $5/$10 game and on the river there is $140 in the pot. Your only opponent checks to you. If you check, you know you've lost. So you bluff. The reasoning is that if you invest another $10, you're getting 14 to 1 odds. As a percent that's around 7%. If they fold more than 7% of the time, you make money in the long poker game of life. If not, it's a losing venture.
You still have to evaluate the player, but from a purely mathematical standpoint, you get the picture. You can also evaluate it by reasoning that they missed their draw more than 7% of the time and will fold.
If two players were involved in the pot, it cuts the odds in half. With three, it becomes 1/3rd of 7%, etc. You can see why you want to bluff against fewer players.
This can be unreliable though, as some players will stay in purely based on pot odds. So when bluffing you cannot ever use just odds. Get a feel for your opponents, and act accordingly.