In February 2011, there is an unexpected temporary surge in the demand for notebook hard drives, increasing the monthly demand for hard drives by 25 percent at any possible price. As a result of this, the price of notebook hard drives increased by $5 per megabyte by the end of February. This surge in demand ended in March 2011, and the price of notebook hard drives fell back to its level just before the temporary demand surge occurred.
Later that year, in August 2011, a permanent increase in the demand for notebook computers occurs, increasing the monthly demand for hard drives by 25 percent per month at any possible price. Nine months later, the price of notebook hard drives had increased, by $1 per unit.
In both circumstances, the market experienced a shift in demand of exactly the same magnitude. Yet, the change in the equilibrium price appears to have been different. Why?