Logit Transformation
Compute the logit transformation of proportions or percentages.
logit(p, percents=range.p[2] > 1, adjust)
p |
numeric vector or array of proportions or percentages. |
percents |
|
adjust |
adjustment factor to avoid proportions of 0 or 1;
defaults to |
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.
a numeric vector or array of the same shape and size as p.
John Fox jfox@mcmaster.ca
Fox, J. and Weisberg, S. (2019) An R Companion to Applied Regression, Third Edition, Sage.
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
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