agricolae (version 1.2-0)

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

Principles and procedures of statistics a biometrical approach Steel & Torry & Dickey. Third Edition 1997

See Also

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

Examples

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()
attach(sweetpotato)
df<-df.residual(model)
MSerror<-deviance(model)/df
comparison <- SNK.test(yield,virus,df,MSerror, group=TRUE)
print(comparison$groups)
detach(sweetpotato)