The More Responsive Quantity Demanded Is to a Change in Price, the More Elastic Is the Demand Curve Beginning at point a, an increase in price from $40 to $50 causes a big decrease in quantity demanded along demand curve E, from 100 units to 20 units at point b. But the same increase in price causes only a small decrease in quantity demanded along demand curve I from 100 to 95 units at point c. Since the quantity demanded is more responsive to a change in price along demand curve E, demand curve E is more elastic than demand curve I.