| aov.ibd {ibd} | R Documentation |
This function performs intrablock analysis of variance of data from experiments using a block design. It also computes least square means of the factor variables (e.g. treatments) and optionally estimates and tests the contrasts of factor variables (e.g treatments).
aov.ibd(formula,specs,data,contrast,joint=FALSE,details=FALSE,sort=TRUE,by=NULL, alpha=0.05,Letters = "ABCDEFGHIJ",...)
formula |
A formula specifying the model of the form response~treatment+block or response~block+treatment. Make sure the treatment and blocks are factor variables. |
specs |
A character vector specifying the names of the factors over which Least square means are desired |
data |
A data frame in which the variables specified in the formula will be found. If missing, the variables are searched for in the standard way. |
contrast |
A matrix whose rows are contrasts of factors (e.g. treatments) |
joint |
If contrast argument has more than one row, then whether a joint test of the contrasts will be performed. Default is FALSE. If joint=TRUE, a check is performed whether the contrasts are pairwise orthogonal or not and then if orthoghonal, joint test is performed. |
details |
Logical, if details=TRUE then all objects including lm object from lm(), lsm object from lsmeans() are returned. Default is FALSE. |
sort |
Logical value determining whether the least square means are sorted before the comparisons are produced. Default is TRUE. |
by |
Character value giving the name or names of variables by which separate families of comparisons are tested. If NULL, all means are compared. |
alpha |
Numeric value giving the significance level for the comparisons |
Letters |
Characters to be used for compact letter display of groups of factor variables over which least square means are computed. Default is english alphabet capital letters "ABCDEFGHIJ" |
... |
Not used |
The function makes use of lm() function in R and Anova() function in car package with specification of Type III sum of squares and lsmeans(), cld(), contrast() functions in lsmeans() package and combines the results in a single place.
Returns a list with following components
lm.obj |
An object of class lm if details=TRUE |
ANOVA.table |
ANOVA table from the fitted lm object |
LSMEANS |
Least square means with compact letter display |
contrast.analysis |
Contrast analysis result if contrast matrix was supplied |
B N Mandal <mandal.stat@gmail.com>
data(ibddata) aov.ibd(y~factor(trt)+factor(blk),data=ibddata) contrast=matrix(c(1,-1,0,0,0,0,0,0,0,0,0,1,-1,0,0,0,0,0),nrow=2,byrow=TRUE) aov.ibd(y~factor(trt)+factor(blk),specs="trt",data=ibddata,contrast=contrast)