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148 • MicroeconomicsPS2S1P 2P1P32D2D1Q3Q Q1Figure 9.1 • Shifting demand and supply curves.Qbacon are likely to shift down as people buy fewer eggs and eat bacon andeggs less often.A change in tastes or information can shift the demand curve. If peopleworry more about cholesterol, they will buy fewer eggs at all prices (ashift downward in the demand curve).To summarize: The demand curve is a relationship between P and Q.Within that given relationship, a change in P causes a change in Q, or viceversa, along the demand curve. But the whole relationship between P andQ can also change. That is a shift in the entire curve. The curve maychange its shape and position, but it will always be downward sloping, atleast in the absence of speculative demand (see Box 8.1).Similar things can be said about a movement along the supply curveand a shift in supply. The discovery of a more efficient technology or anew deposit of resources, for example, would shift the supply curve outwardso that more would be offered at each price.The impacts of shifting supply and demand curves on equilibrium priceand output are shown in Figure 9.1. A massive recall of E. coli–tainted beefand a closing of the guilty processing plant might shift the supply curvefor beef from S 1 to S 2 . In response to the shift, prices would rise along theD 1 curve, from P 1 to P 2 , and supply would drop from Q 1 to Q 2 . The recallleads to a series of investigative reports on conditions in meat-packingplants, showing that crowded conditions, rapid processing, and poorinspections make bacterial infection a regular and recurring problem. Inresponse, the demand for beef might shift from D 1 to D 2 . As a response to