A name of this measure?

#1
How to name chg1/chg2 or is there any related (better/recognized) measure?

before after chg1 chg2 chg1/chg2

2 1 -1 2 -0.5
20 10 -10 2 -5
40 20 -20 2 -10
80 40 -40 2 -20
100 50 -50 2 -25

1 2 1 2 0.5
10 20 10 2 5
20 40 20 2 10
40 80 40 2 20
50 100 50 2 25