Three different types of cage are tested on the growth of Aedes intrudens, a kind of mosquito pupae. In each one, four mosquitos are added and its wings measured twice. There are 24 observations (3 cages X 4 jars X 2 measures).
This design was extracted from Underwood (1997) but data are artificial. Snails were transplanted from origin to different shores. Several boulders were used on each shore. Cages with snail of each origin on each boulder were replicated. All factors (origin, shore, boulder and cage) are random.
providing 
.