When all we know is that demand has shifted out (increased) and supply has shifted back (decreased) we can say for certain that the equilibrium price will increase, but we cannot know if the equilibrium quantity will increase or decrease.

As the graph to the right shows, if demand had shifted out a bit more, would have been greater than , meaning the equilibrium quantity would have would have risen. However, if demand had shifted a bit less than originally, would have been to the left of, or smaller than , meaning the equilibrium quantity would have fallen.

Alternatively, if supply had shifted back a bit more, the equilibrium quantity would have fallen, but if it had shifted back a bit less, the equilibrium quantity would have risen.

Since all we knew here was that demand shifted out (increased) and supply shifted back (decreased), we could not predict the change in equilibrium quantity. Thus, in this case, the change in equilibrium quantity is indeterminate.