The
Sitka89
data frame has 632 rows and 4
columns. It gives repeated measurements on the log-size of 79 Sitka
spruce trees, 54 of which were grown in ozone-enriched chambers and 25
were controls. The size was measured eight times in 1989, at roughly
monthly intervals.
This data frame contains the following columns:
"ozone"
for an ozone-enriched
chamber or
"control"
P. J. Diggle, K.-Y. Liang and S. L. Zeger (1994) Analysis of Longitudinal Data. Clarendon Press, Oxford