VCA (version 1.5.1)

getSSQsweep: ANOVA Sum of Squares via Sweeping

Description

Compute ANOVA Type-1 sum of squares for linear models.

Usage

getSSQsweep(Data, tobj, random = NULL)

Value

(list) representing the with variables:

aov.tab

basic ANOVA-table with degrees of freedom (DF), SS and MS

Lmat

(list) with components 'Z' and 'A'

Arguments

Data

(data.frame) with the data

tobj

(terms) object derived from original formula object

random

(character) vector, optionally containing information about each model term, whether it is random or fixed (only used in mixed models)

Author

Andre Schuetzenmeister , Florian Dufey

Details

This function performs estimation of ANOVA Type-1 sum of squares using the SWEEP-operator (see reference), operating on the augmented matrix \(X'X\), where \(X\) represents the design matrix not differentiating between fixed and random factors. See the numerical example in Fsweep exemplifying the type of augmentation of \(X'X\) on which sweeping is carried out.

This is an utility function not intended to be called directly. For each term in the formula the design-matrix \(Z\) is constructed. Matrix \(X\) corresponds to binding all these \(Z\)-matrices together column-wise.

Degrees of freedom for each term are determined by subtracting the number of linearly dependent columns from the total number of column in X asigned to a specific term.

References

Goodnight, J.H., (1979), A Tutorial on the SWEEP Operator, The American Statistician, 33:3, p.149-158

See Also

Fsweep

Examples

if (FALSE) {
data(dataEP05A2_1)
res <- VCA:::getSSQsweep(dataEP05A2_1, terms(y~day/run))
str(res)
}