Compute Efficiencies of Multistratum Analysis of Variance

Usage

eff.aovlist(aovlist)

Arguments

aovlist The result of a call to aov with a Error term.

Description

~~ A concise (1-5 lines) description of what the function does. ~~

Details

Fixed-effect terms in an analysis of variance model with multiple strata may be estimable in more than one stratum, in which case there is less than complete information in each. The efficiency is the fraction of the maximum possible precision (inverse variance) obtainable by estimating in just that stratum.

This is used to pick strata in which to estimate terms in model.tables.aovlist and elsewhere.

Value

A matrix giving for each non-pure-error stratum (row) the efficiencies for each fixed-effect term in the model.

Author(s)

B.D. Ripley

See Also

aov, model.tables.aovlist, se.contrast.aovlist

Examples

## for balanced designs all efficiencies are zero or one.
## so as a statistically meaningless test:
options(contrasts=c("contr.helmert", "contr.poly"))
## From Venables and Ripley (1997) p.210.
N <- c(0,1,0,1,1,1,0,0,0,1,1,0,1,1,0,0,1,0,1,0,1,1,0,0)
P <- c(1,1,0,0,0,1,0,1,1,1,0,0,0,1,0,1,1,0,0,1,0,1,1,0)
K <- c(1,0,0,1,0,1,1,0,0,1,0,1,0,1,1,0,0,0,1,1,1,0,1,0)
yield <- c(49.5,62.8,46.8,57.0,59.8,58.5,55.5,56.0,62.8,55.8,69.5,
55.0, 62.0,48.8,45.5,44.2,52.0,51.5,49.8,48.8,57.2,59.0,53.2,56.0)

npk <- data.frame(block=gl(6,4), N=factor(N), P=factor(P),
                  K=factor(K), yield=yield)
npk.aovE <- aov(yield ~  N*P*K + Error(block), npk)
eff.aovlist(npk.aovE)

[Package Contents]