phrase. If you say that the odds are against something or someone, you mean that they are unlikely to succeed. He reckoned the odds are against the scheme going ahead. I'm sorry.

To find an odds ratio from a given probability, first express the probability as a fraction (we'll use 5/13). Subtract the numerator (5) from the denominator (13) : 13 - 5 = 8 . The answer is the number of unfavorable outcomes. Odds can then be expressed as 5 : 8 - the ratio of favorable to unfavorable outcomes.