Sitka89 {MASS} | R Documentation

## Growth Curves for Sitka Spruce Trees in 1989

### Description

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.

### Usage

    data(Sitka89)

### Format

This data frame contains the following columns:

`size`
  measured size (height times diameter squared) of tree, on log scale.
`Time`
  time of measurement in days since 1 January 1988
`tree`
  number of tree
`treat`
  either `"ozone"` for an ozone-enriched chamber or `"control"`

### Source

P. J. Diggle, K.-Y. Liang and S. L. Zeger (1994) Analysis of Longitudinal Data. Clarendon Press, Oxford

### See Also

`Sitka`