Convert Probability to Odds

odds() converts a probability to the corresponding odds.

prob_from_odds() converts odds to the corresponding proability.

Usage

odds(x)

prob_from_odds(x)

Arguments

x

a probability from which to derive the odds, or odds from which to derive the probability.

Value

odds returns the derived odds; prob_from_odds returns the derived probability.

Details

The odds are defined as \(\log(p / q)\) where \(q = 1 - p\).

The probability may be calculated from the odds by the inverse transformation: -

$$p = \displaystyle \frac{odds}{1 + odds}$$

See also

Other odds-logit: logit()

Examples

odds(0.5)
#> [1] 1
prob_from_odds(1)
#> [1] 0.5

(s <- seq(from = 0, to = 1, by = 0.125))
#> [1] 0.000 0.125 0.250 0.375 0.500 0.625 0.750 0.875 1.000
(s <- odds(s))
#> [1] 0.0000000 0.1428571 0.3333333 0.6000000 1.0000000 1.6666667 3.0000000
#> [8] 7.0000000       Inf
prob_from_odds(s)
#> [1] 0.000 0.125 0.250 0.375 0.500 0.625 0.750 0.875 1.000

rm(s)