Also posted 19 February 2018:

James wrote, “<em>I must remember next time I try to compare the average height of a giraffe to the average height of a human, that it cannot be done because the units are incompatible. </em>”

Average height of a giraffe, say 5.5 meters/giraffe.

Average height of a human, say, 1.6 meters/human.

Giraffes are taller then humans, on average.

Glad I could clear that up for you.