The midpoint method is used to calculate elasticity between two points because it gives the same answer regardless of the direction of the change.

The midpoint method calculates elasticity as the percentage change in quantity divided by the percentage change in price, using the average of the initial and final quantities and prices. This approach yields the same elasticity value whether we move from point A to point B or from point B to point A, ensuring consistency in elasticity calculations regardless of the direction of change.