Onions data

Description

The onions data frame contains 84 sets of observations from an experiment involving the production of white Spanish onions in two South Australian locations.

Usage

data(onions)

Format

This data frame contains the following columns:

dens

areal density of plants (plants per square metre)

yield

onion yield (grammes per plant).

location

indicator of location: 0=Purnong Landing, 1=Virginia.

Source

Ratkowsky, D. A. (1983). Nonlinear Regression Modeling: A Unified Practical Approach. New York: Marcel Dekker.

References

Ruppert, D., Wand, M.P. and Carroll, R.J. (2003)
Semiparametric Regression Cambridge University Press.
http://stat.tamu.edu/~carroll/semiregbook/

Examples

library(SemiPar)
data(onions)
attach(onions)
points.cols <- c("red","blue")
plot(dens,yield,col=points.cols[location+1],pch=16)
legend(100,250,c("Purnong Landing","Virginia"),col=points.cols,pch=rep(16,2))