ortho {asuR} | R Documentation |
This function tests all pairwise contrast coefficients for orthogonality. The function tells the user which pair of contrasts are not orthogonal.
ortho(contr, round = 10)
contr |
A matirx, wiht k-1 rows (one for each contrast) and k columns one for each level of a factor. |
round |
To test if the sum of the products of the coefficients is zero the sum is rounded using this value as digits argument for round. |
For all pairs of contrasts coefficients the sum of the products of the coefficients is calculated and compared if it is zero or not.
a logical
There are more elegant solutions to this problem but this one tells the user which pairs of contrasts are not orthogonal.
none
trt.contr <- rbind("control-sugar"=c(1, -1/4, -1/4, -1/4, -1/4), "pure-mixed"=c(0, 1/3, 1/3, -1, 1/3), "monosaccharides-disaccharides"=c(0,1/2,1/2,0,-1), "gluc-fruc"=c(0,1,-1,0,0)) ortho(trt.contr)