From Basic Practice of Statistics, 7th ed., problem 28.48:
A botanist prepares 16 identical planting pots and then introduces
different numbers of nematodes (microscopc worms) into the pots.  A
tomato seedling is transplanted into each pot.  Here are data on the
increas in height of the seedlings in centimeters 16 days after
planting.

Variables:
  number of nematodes in thousands
  seedling growth in centimeters