contest1D.lmerModLmerTest {lmerTest} | R Documentation |
Contrast Tests in 1D
Description
Compute the test of a one-dimensional (vector) contrast in a linear mixed model fitted with lmer from package lmerTest. The contrast should specify a linear function of the mean-value parameters, beta. The Satterthwaite or Kenward-Roger method is used to compute the (denominator) df for the t-test.
Usage
## S3 method for class 'lmerModLmerTest'
contest1D(
model,
L,
rhs = 0,
ddf = c("Satterthwaite", "Kenward-Roger"),
confint = FALSE,
level = 0.95,
...
)
## S3 method for class 'lmerMod'
contest1D(
model,
L,
rhs = 0,
ddf = c("Satterthwaite", "Kenward-Roger"),
confint = FALSE,
level = 0.95,
...
)
Arguments
model |
a model object fitted with |
L |
a numeric (contrast) vector of the same length as
|
rhs |
right-hand-side of the statistical test, i.e. the hypothesized value (a numeric scalar). |
ddf |
the method for computing the denominator degrees of freedom.
|
confint |
include columns for lower and upper confidence limits? |
level |
confidence level. |
... |
currently not used. |
Details
The t-value and associated p-value is for the hypothesis
L' \beta = \mathrm{rhs}
in which rhs may be non-zero
and \beta
is fixef(model)
.
The estimated value ("Estimate"
) is L' \beta
with associated
standard error and (optionally) confidence interval.
Value
A data.frame
with one row and columns with "Estimate"
,
"Std. Error"
, "t value"
, "df"
, and "Pr(>|t|)"
(p-value). If confint = TRUE
"lower"
and "upper"
columns
are included before the p-value column.
Author(s)
Rune Haubo B. Christensen
See Also
contest
for a flexible
and general interface to tests of contrasts among fixed-effect parameters.
contestMD
is also available as a
direct interface for tests of multi degree-of-freedom contrast.
Examples
# Fit model using lmer with data from the lme4-package:
data("sleepstudy", package="lme4")
fm <- lmer(Reaction ~ Days + (1 + Days|Subject), sleepstudy)
# Tests and CI of model coefficients are obtained with:
contest1D(fm, c(1, 0), confint=TRUE) # Test for Intercept
contest1D(fm, c(0, 1), confint=TRUE) # Test for Days
# Tests of coefficients are also part of:
summary(fm)
# Illustrate use of rhs argument:
contest1D(fm, c(0, 1), confint=TRUE, rhs=10) # Test for Days-coef == 10