contrasts {factDesign}R Documentation

Construct appropriate lambda matrix and test linear contrasts of the parameter estimates from a linear model.


'par2lambda' takes list of lm coefficient names and a corresponding list of numeric vectors corresponding to hypothesis tests of linear contrasts and returns a lambda matrix suitable for an F-test of the linear contrasts. 'par2lambda' is intended to be used in conjunction with 'contrastTest' or 'findFC'.

'contrastTest' performs an F test for simultaneous tests of linear contrasts using an appropriately specified lambda matrix and an lm object.


par2lambda(betaNames, betas, coefs)
contrastTest(model, lambda, cVec = NA, p = 0.01)


betaNames A character vector of the names of the coefficients in a linear model.
betas A list of vectors of the parameters to be used in the contrasts.
coefs A list of vectors of numeric coefficients corresponding to betas.
model An lm object.
lambda A matrix of coefficients in the appropriate order to be multiplied by the estimated coefficients of the lm object, possibly returned from 'par2lambda'.
cVec A vector of constants for testing that the linear contrasts equal something other than zero. If this is unspecified, it is assumed to be zero.
p The significance level at which to perform the contrast test.


For par2lambda: A lambda matrix constructed for testing linear contrasts using lm output.
For contrastTest:

test Returns "REJECT" or "FAIL TO REJECT" based on the result of the test of hypothesis.
Fstat The F statistic for the test of contrast.
pvalue The corresponding pvalue for the F test.
cEst The contrast estimate.


Denise Scholtens

See Also



ES <- pData(estrogen)[["ES"]]
TIME <- pData(estrogen)[["TIME"]]   
fit <- lm(exprs(estrogen)["40079_at",] ~ ES + TIME + ES*TIME)
betaNames <- names(fit[["coef"]])
betas <- list(c("ESP"),c("ESP","ESP:TIME48h"))
coefs <- list(c(1),c(1,1))
lambda <- par2lambda(betaNames,betas,coefs)

[Package factDesign version 1.1.4 Index]