fac.meanop {dae}R Documentation

computes the projection matrix that produces means


Computes the symmetric projection matrix that produces the means corresponding to a (generalized) factor.





The (generalized) factor whose means the projection matrix computes from an observation-length vector.


The design matrix X for a (generalized) factor is formed with a column for each level of the (generalized) factor, this column being its indicator variable. The projection matrix is formed as X %*% (1/diag(r) %*% t(X), where r is the vector of levels replications.

A generalized factor is a factor formed from the combinations of the levels of several original factors. Generalized factors can be formed using fac.combine.


A projector containing the symmetric, projection matrix and its degrees of freedom.


Chris Brien

See Also

fac.combine, projector, degfree, correct.degfree, fac.sumop in package dae.

projector for further information about this class.


## set up a two-level factor and a three-level factor, both of length 12
A <- factor(rep(1:2, each=6))
B <- factor(rep(1:3, each=2, times=2))

## create a generalized factor whose levels are the combinations of A and B
AB <- fac.combine(list(A,B))

## obtain the operator that computes the AB means from a vector of length 12
M.AB <- fac.meanop(AB)

[Package dae version 3.2-13 Index]