H1:

Selling, General and Administrative costs (SGA) are sticky to changes in sales level. For acceptance of this hypothesis, in model (1.a) β₁ should be >0 and β₂ < 0.

H2:

Cost of Goods Sold (COGS) is sticky to changes in sales level. For acceptance of this hypothesis, in model (1.b) β₁ should be >0 and β₂ < 0.