gomez.nitrogen {agridat} | R Documentation |
Soil nitrogen at three times for eight fertilizer treatments
Description
Soil nitrogen at three times for eight fertilizer treatments
Format
A data frame with 96 observations on the following 4 variables.
trt
nitrogen treatment factor
nitro
soil nitrogen content, percent
rep
replicate
stage
growth stage, three periods
Details
Eight fertilizer treatments were tested.
Soil nitrogen content was measured at three times. P1 = 15 days post transplanting. P2 = 40 days post transplanting. P3 = panicle initiation.
Used with permission of Kwanchai Gomez.
Source
Gomez, K.A. and Gomez, A.A.. 1984, Statistical Procedures for Agricultural Research. Wiley-Interscience. Page 259.
References
R-help mailing list, 9 May 2013. Data provided by Cyril Lundrigan. Analysis method by Rich Heiberger.
Examples
library(agridat)
data(gomez.nitrogen)
dat <- gomez.nitrogen
# Note the depletion of nitrogen over time (stage)
libs(HH)
interaction2wt(nitro ~ rep/trt + trt*stage, data=dat,
x.between=0, y.between=0,
main="gomez.nitrogen")
# Just the fertilizer profiles
with(dat, interaction.plot(stage, trt, nitro,
col=1:4, lty=1:3, main="gomez.nitrogen",
xlab="Soil nitrogen at three times for each treatment"))
# Gomez table 6.16
m1 <- aov(nitro ~ Error(rep/trt) + trt*stage, data=dat)
summary(m1)
# Gomez table 6.18
# Treatment 1 2 3 4 5 6 7 8
cont <- cbind("T7 vs others" = c( 1, 1, 1, 1, 1, 1,-7, 1),
"T8 vs others" = c( 1, 1, 1, 1, 1, 1, 0,-6),
"T2,T5 vs others" = c(-1, 2,-1,-1, 2,-1, 0, 0),
"T2 vs T5" = c( 0, 1, 0, 0,-1, 0, 0, 0))
contrasts(dat$trt) <- cont
contrasts(dat$trt)
m2 <- aov(nitro ~ Error(rep/trt) + trt*stage, data=dat)
summary(m2, expand.split=FALSE,
split=list(trt=list(
"T7 vs others"=1,
"T8 vs others"=2,
"T2,T5 vs others"=3,
"T2 vs T5"=4,
rest=c(5,6,7)),
"trt:stage"=list(
"(T7 vs others):P"=c(1,8),
"(T8 vs others):P"=c(2,9),
"(T2,T5 vs others):P"=c(3,10),
"(T2 vs T5):P"=c(4,11),
"rest:P"=c(5,6,7,12,13,14))
))
[Package agridat version 1.23 Index]