Walker (1962) studied the mating songs of male
tree crickets. Each wingstroke by a cricket produces a pulse of
song, and females may use the number of pulses per second to
identify males of the correct species. Walker (1962) wanted to
know whether the chirps of the crickets Oecanthus
exclamationis and Oecanthus niveus had different pulse
rates. See https://www.biostathandbook.com/ancova.html for
details. He measured the pulse rate of the crickets (variable
pps) at a variety of temperatures (temp):