logit {car} | R Documentation |
Logit Transformation
Description
Compute the logit transformation of proportions or percentages.
Usage
logit(p, percents=range.p[2] > 1, adjust)
Arguments
p |
numeric vector or array of proportions or percentages. |
percents |
|
adjust |
adjustment factor to avoid proportions of 0 or 1;
defaults to |
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
.
Author(s)
John Fox jfox@mcmaster.ca
References
Fox, J. and Weisberg, S. (2011) An R Companion to Applied Regression, Second Edition, Sage.
See Also
Examples
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)
logit(.1*0:10, adjust=0)
## [1] -Inf -2.1972 -1.3863 -0.8473 -0.4055 0.0000 0.4055
## [8] 0.8473 1.3863 2.1972 Inf
[Package car version 2.0-22 Index]