Onions data

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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

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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

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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))