logit and inverse logit (expit) functions
logit(x, low = 0, high = 1)
expit(alpha, low = 0, high = 1)
logitNormInfo(mean = 0, sd = 1, low = 0, high = 1, abs.tol = 1e-06, ...)
probitNormInfo(mean = 0, sd = 1, low = 0, high = 1, abs.tol = 1e-06, ...)
x | Input value(s) in range [low,high] to translate -Inf to Inf |
---|---|
low | Lowest value in the range |
high | Highest value in the range |
alpha | Infinite value(s) to translate to range of [low, high] |
mean | logit-scale mean |
sd | logit-scale standard deviation |
abs.tol | absolute accuracy requested. |
... | other parameters passed to |
values from logit and expit
logit is given by:
logit(p) = -log(1/p-1)
where:
p = x-low/high-low
expit is given by:
expit(p, low, high) = (high-low)/(1+exp(-alpha)) + low
The logitNormInfo()
gives the mean, variance and coefficient of
variability on the untransformed scale.
logit(0.25)
#> [1] -1.098612
expit(-1.09)
#> [1] 0.2516183
logitNormInfo(logit(0.25), sd = 0.1)
#> mean var cv
#> 0.2504672899 0.0003515538 0.0748591440
logitNormInfo(logit(1, 0, 10), sd = 1, low = 0, high = 10)
#> mean var cv
#> 1.3386966 1.2662276 0.8405697