gamlss.data (version 6.0-6)

tidal: The tidal data set

Description

The dataset tidal, McArdle and Anderson (2004), gives counts of the organism "intertidal bivalve A. Stutchburyi" in three tidal areas in the Bay of Plenty, New Zealand.

Usage

data("tidal")

Format

A data frame with 90 observations on the following 3 variables.

number

count of A. Stutchburyi organisms

vertht

vertical tidal height (m)

ht

tidal area, a factor with three level

Details

The dataset gives counts of the organism "intertidal bivalve A. Stutchburyi" in three tidal areas in the Bay of Plenty, New Zealand. Each observation is the count of the number of these organisms in a 0.25 m quadrat, as well as the vertical tidal height of the quadrat. The vertical heights have been classified into three tidal areas: upper (vertical height > 0.66m), middle (0.33- 0.66 m) and lower (<0.33 m). Ecologists are interested in the effect of tidal height (either raw or classified) on the number of organisms.

References

McArdle, B. H. and Anderson, M. J. (2004), Variance heterogeneity, transformations, and models of species abundance: a cautionary tale, Canadian Journal of Fisheries and Aquatic Sciences, 7, vol 61, pp 1294-1302, NRC Research Press.

Examples

str(tidal)
plot(number~vertht, data=tidal)
plot(number~ht, data=tidal)