Which of the following correctly describes Musgrave and Thin's measure of tax progressivity?
where
Ga = Gini's coefficient after tax,
Gb = Gini's coefficient before tax.
1
\(M =\frac{1-G_a}{1-G_b}\)
2
\(M =\frac{G_a}{G_b} \)
3
\(M =\frac{1-G_b}{1-G_a}\)
4
\(\mathrm{M}=\frac{\mathrm{G}_{\mathrm{b}}}{\mathrm{G}_{\mathrm{a}}}\)