Compute the logit transformation of proportions or percentages.
logit(p, percents=range.p[2] > 1, adjust)
numeric vector or array of proportions or percentages.
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.
a numeric vector or array of the same shape and size as p
.
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.
Fox, J. and Weisberg, S. (2019) An R Companion to Applied Regression, Third Edition, Sage.
# 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) 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 # }