logit

0th

Percentile

Logit Transformation

Compute the logit transformation of proportions or percentages.

Keywords
manip
Usage
logit(p, percents=range.p[2] > 1, adjust)
Arguments
p

numeric vector or array of proportions or percentages.

percents

TRUE for percentages.

adjustment factor to avoid proportions of 0 or 1; defaults to 0 if there are no such proportions in the data, and to .025 if there are.

Details

Computes the logit transformation logit $=\log [p/(1-p)]$ for the proportion $p$.

If $p=0$ or $1$, then the logit is undefined. logit can remap the proportions to the interval (adjust, 1 - adjust) prior to the transformation. If it adjusts the data automatically, logit will print a warning message.

Value

a numeric vector or array of the same shape and size as p.

References

Fox, J. and Weisberg, S. (2019) An R Companion to Applied Regression, Third Edition, Sage.

probabilityAxis

• logit
Examples
# NOT RUN {
options(digits=4)
logit(.1*0:10)
##  [1] -3.6636 -1.9924 -1.2950 -0.8001 -0.3847  0.0000  0.3847
##  [8]  0.8001  1.2950  1.9924  3.6636
## Warning message:
## proportions remapped to (0.025, 0.975) in: logit(0.1 * 0:10)