holshouser.splitstrip {agridat} | R Documentation |
Split strip plot on soybeans
A data frame with 160 observations on the following 8 variables.
block
block factor, 4 levels
plot
plot number
cultivar
cultivar factor, 4 levels
spacing
row spacing
pop
population (thousand per acre)
yield
yield
row
row
col
column
Within each block, cultivars were whole plots. Withing whole plots, spacing was applied in strips vertically, and population was applied in strips horizontally.
Schabenberger, Oliver and Francis J. Pierce. 2002. Contemporary Statistical Models for the Plant and Soil Sciences. CRC Press, Boca Raton, FL. Page 493.
Used with permission of David Holshouser at Virginia Polytechnic.
data(holshouser.splitstrip) dat <- holshouser.splitstrip dat$spacing <- factor(dat$spacing) dat$pop <- factor(dat$pop) # Experiment layout and field trends if(require(desplot)){ desplot(yield ~ col*row, data=dat, out1=block, # unknown aspect main="holshouser.splitstrip") desplot(spacing ~ col*row, data=dat, out1=block, out2=cultivar, # unknown aspect col=cultivar, text=pop, cex=.8, shorten='none', col.regions=c('wheat','white'), main="holshouser.splitstrip experiment design") } # Overall main effects and interactions if(require(HH)){ interaction2wt(yield~cultivar*spacing*pop, dat, x.between=0, y.between=0, main="holshouser.splitstrip") } ## Schabenberger's SAS model, page 497 ## proc mixed data=splitstripplot; ## class block cultivar pop spacing; ## model yield = cultivar spacing spacing*cultivar pop pop*cultivar ## spacing*pop spacing*pop*cultivar / ddfm=satterth; ## random block block*cultivar block*cultivar*spacing block*cultivar*pop; ## run; ## Not run: ## Now lme4. This design has five error terms--four are explicitly given. require(lme4) require(lucid) m1 <- lmer(yield ~ cultivar * spacing * pop + (1|block) + (1|block:cultivar) + (1|block:cultivar:spacing) + (1|block:cultivar:pop), data=dat) vc(m1) ## Variances match Schabenberger, page 498. ## grp var1 var2 vcov sdcor ## block:cultivar:pop (Intercept) <NA> 2.421 1.556 ## block:cultivar:spacing (Intercept) <NA> 1.244 1.116 ## block:cultivar (Intercept) <NA> 0.4523 0.6725 ## block (Intercept) <NA> 3.037 1.743 ## Residual <NA> <NA> 3.928 1.982 ## End(Not run)