agricolae (version 1.2-6)

SNK.test: Student-Newman-Keuls (SNK)

Description

SNK is derived from Tukey, but it is less conservative (finds more differences). Tukey controls the error for all comparisons, where SNK only controls for comparisons under consideration. The level by alpha default is 0.05.

Usage

SNK.test(y, trt, DFerror, MSerror, alpha = 0.05, 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

Degree free

MSerror

Mean Square Error

alpha

Significant level

group

TRUE or FALSE

main

Title

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

group

Logic

main

Text

Details

It is necessary first makes a analysis of variance.

References

1. Principles and procedures of statistics a biometrical approach Steel & Torry & Dickey. Third Edition 1997 2. Multiple comparisons theory and methods. Departament of statistics the Ohio State University. USA, 1996. Jason C. Hsu. Chapman Hall/CRC.

See Also

LSD.test, waller.test , HSD.test , duncan.test

Examples

# NOT RUN {
library(agricolae)
data(sweetpotato)
model<-aov(yield~virus,data=sweetpotato)
comparison <- SNK.test(model,"virus", 
main="Yield of sweetpotato. Dealt with different virus")
SNK.test(model,"virus", group=FALSE)
# version old SNK.test()
df<-df.residual(model)
MSerror<-deviance(model)/df
comparison <- with(sweetpotato,SNK.test(yield,virus,df,MSerror, group=TRUE))
print(comparison$groups)
# }