SemiPar (version 1.0-4.2)

sitka: Sitka spruce data

Description

The sitka data frame contains measurements of log-size for 79 Sitka spruce trees grown in normal or ozone-enriched environments. Within each year, the data are organised in four blocks, corresponding to four controlled environment chambers. The first two chambers, containing 27 trees each, have an ozone-enriched atmosphere, the remaining two, containing 12 and 13 trees respectively, have a normal (control) atmosphere.

Usage

data(sitka)

Format

This data frame contains the following columns:

id.num

identification number of tree.

order

time order ranking within each tree.

days

time in days since 1st January, 1988.

log.size

tree size measured on a logarithmic scale.

ozone

indicator ozone treatment: 0=control,1=ozone.

References

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

Examples

# NOT RUN {
library(SemiPar)
data(sitka)
attach(sitka)
library(lattice)
ozone.char <- rep("control",nrow(sitka))
ozone.char[ozone==1] <- "ozone"
xyplot(log.size~days|ozone.char,data=sitka,groups=id.num,type="b")
# }