agricolae (version 1.2-6)

LSD.test: Multiple comparisons, "Least significant difference" and Adjust P-values

Description

Multiple comparisons of treatments by means of LSD and a grouping of treatments. The level by alpha default is 0.05. Returns p-values adjusted using one of several methods

Usage

LSD.test(y, trt, DFerror, MSerror, alpha = 0.05, p.adj=c("none","holm","hommel", 
"hochberg", "bonferroni", "BH", "BY", "fdr"), group=TRUE, main = NULL,console=FALSE)

Arguments

y

model(aov or lm) or answer of the experimental unit

trt

Constant( only y=model) or vector treatment applied to each experimental unit

DFerror

Degrees of freedom of the experimental error

MSerror

Means square error of the experimental

alpha

Level of risk for the test

p.adj

Method for adjusting p values (see p.adjust)

group

TRUE or FALSE

main

title of the study

console

logical, print output

Value

y

class (aov or lm) or vector numeric

trt

constant (only y=model) or vector alfanumeric

DFerror

Numeric

MSerror

Numeric

alpha

Numeric

p.adj

text, see p.adjust

group

Logic

main

Numeric

Details

For equal or different repetition. p.adj = "holm", "hommel", "hochberg", "bonferroni", "BH", "BY", "fdr". see p.adjust() p-adj ="none" is t-student. p-adj ="hommel" is not applied in this test.

References

Steel, R.; Torri,J; Dickey, D.(1997) Principles and Procedures of Statistics A Biometrical Approach. pp178.

See Also

HSD.test, waller.test, SNK.test , bar.err, bar.group,duncan.test

Examples

# NOT RUN {
library(agricolae)
data(sweetpotato)
model<-aov(yield~virus, data=sweetpotato)
out <- LSD.test(model,"virus", p.adj="bonferroni")
#stargraph
bar.group(out$groups,ylim=c(0,45),density=4,border="blue")
#endgraph
# Old version LSD.test()
df<-df.residual(model)
MSerror<-deviance(model)/df
out <- with(sweetpotato,LSD.test(yield,virus,df,MSerror, p.adj="bonferroni", 
group=FALSE))
#stargraph
# Variation range: Max - Min
bar.err(out$means,variation="range",ylim=c(0,44),bar=FALSE,col=0)
#endgraph
LSD.test(model,"virus",p.adj="bon",console=TRUE)
# }