Fertilizer {mvinfluence}

Fertilizer Data

Description

A small data set on the use of fertilizer (x) in relation to the amount of grain (y1) and straw (y2) produced.

Format

A data frame with 8 observations on the following 3 variables.

grain

amount of grain produced

straw

amount of straw produced

fertilizer

amount of fertilizer applied

Details

The first observation is an obvious outlier and influential observation.

Source

Anderson, T. W. (1984). An Introduction to Multivariate Statistical Analysis, New York: Wiley, p. 369.

References

Hossain, A. and Naik, D. N. (1989). Detection of influential observations in multivariate regression. Journal of Applied Statistics, 16 (1), 25-37.

Examples

data(Fertilizer)

# simple plots
plot(Fertilizer, col=c('red', rep("blue",7)), 
     cex=c(2,rep(1.2,7)), 
     pch=as.character(1:8))

# A biplot shows the data in 2D. It gives another view of how case 1 stands out in data space
biplot(prcomp(Fertilizer))

# fit the mlm
mod <- lm(cbind(grain, straw) ~ fertilizer, data=Fertilizer)
Anova(mod)

# influence plots (m=1)
influencePlot(mod)
influencePlot(mod, type='LR')
influencePlot(mod, type='stres')