Computes confidence intervals for one or more parameters in a fitted model. There is a default and a method for objects inheriting from class
confint(object, parm, level = 0.95, ...)
- a fitted model object.
- a specification of which parameters are to be given confidence intervals, either a vector of numbers or a vector of names. If missing, all parameters are considered.
- the confidence level required.
- additional argument(s) for methods.
confint is a generic function. The default method assumes asymptotic normality, and needs suitable
vcov methods to be available. The default method can be called directly for comparison with other methods.
For objects of class
"lm" the direct formulae based on t values are used.
There are stub methods for classes
"nls" which invoke those in package MASS which are based on profile likelihoods.
A matrix (or vector) with columns giving lower and upper confidence limits for each parameter. These will be labelled as (1-level)/2 and 1 - (1-level)/2 in % (by default 2.5% and 97.5%).
confint.nls in package MASS.
fit <- lm(100/mpg ~ disp + hp + wt + am, data = mtcars) confint(fit) confint(fit, "wt") ## from example(glm) (needs MASS to be present on the system) counts <- c(18,17,15,20,10,20,25,13,12) outcome <- gl(3, 1, 9); treatment <- gl(3, 3) glm.D93 <- glm(counts ~ outcome + treatment, family = poisson()) confint(glm.D93) confint.default(glm.D93) # based on asymptotic normality
Documentation reproduced from R 2.15.3. License: GPL-2.