From West Bay, 20 clam colonies were randomly selected, and from each a sample of clams were taken. Each sample was sieved into three size ranges, large, medium, and small. Then each size range was sorted by the shale colour, dark or light.
data(ClamWest)The data consist of 20 cases and \(2\times 3\) variables denoted:
| dl | portion of dark large clams, | |
| dm | portion of dark medium clams, | |
| ds | portion of dark small clams, | |
| ll | portion of light large clams, | |
| lm | portion of light medium clams, | |
| ls | portion of light small clams. |
All 6-part compositions sum up to one.
Aitchison: The Statistical Analysis of Compositional Data, 1986, Data 15, pp17.