Is a bet at +150 a good one? It depends entirely on what you think the win chance is. Positive expected value means your estimate beats the price's break-even point, and this lesson works the numbers. At +150 the break-even is 40 percent, so a 45 percent estimate gives a modeled gain of $12.50 per $100, while a true 38 percent turns the same bet negative. A small sensitivity table shows how fast the sign flips. You also learn how researchers build probability estimates, how to use an EV interface without over-trusting it, and the failure modes that fool people. A bet that loses often can still be a good price. A favorite can still be a bad one.
Learning objectives
Calculate expected return using a probability estimate and quoted odds; identify the threshold for positive EV; understand why estimated positive EV does not mean a certain profit.
