ratkowsky.onions: Onion yields for different densities at two locations

ratkowsky.onionsR Documentation

Onion yields for different densities at two locations

Description

Onion yields for different densities at two locations

Format

This data frame contains the following columns:

density

planting density (plants per square meter)

yield

yield (g / plant)

loc

location, Purnong Landing or Virginia

Details

Spanish white onions.

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. https://stat.tamu.edu/~carroll/semiregbook/

Examples

## Not run: 

library(agridat)
data(ratkowsky.onions)
dat <- ratkowsky.onions

# Model inverse yield as a quadratic.  Could be better...
libs(lattice)
dat <- transform(dat, iyield = 1/yield)
m1 <- lm(iyield ~ I(density^2)*loc, dat)
dat$pred <- predict(m1)

libs(latticeExtra)
foo <- xyplot(iyield ~ density, data=dat, group=loc, auto.key=TRUE,
               main="ratkowski.onions",ylab="Inverse yield")
foo + xyplot(pred ~ density, data=dat, group=loc, type='l')


## End(Not run)

kwstat/agridat documentation built on March 28, 2024, 9:45 a.m.