Change in Supply vs. Change in Quantity Supplied

… a core concept in Economic Analysis

Click for MRU video

Click for MRU video

Concept description

In his MRU lesson, Alex Tabarrok (reference below and video to right) underlines the crucial distinction between a change in supply (a shift in the supply curve caused by one of the supply curve shifters) and a change in the quantity supplied (a movement along the same supply curve caused by a change in the price due to a change in demand).

This is illustrated in the figure. In the left graph the supply increases as a result of the shift in the supply curve. In the right graph the quantity supplied increases because increased demand (a shift of the black line to the right) has increased the equilibrium price for the same supply curve.

MRU practice questions

See, accessed 20 April 2016:

  1. When supply falls, what happens to quantity demanded in equilibrium?
    1. Q


Alex Tabarrok, Supply and Demand Terminology, Marginal Revolution University, at, accessed 20 April 2016.

Atlas topic and subject

Supply, Demand, and Equilibrium (core topic) in Economic Analysis.

Page created by: Ian Clark, last modified on 20 April 2016.

Image: Minute 3:09 of MRU Video, at, accessed 20 April 2016.