This pattern of price and output changes is inconsistent with the Keynesian model un- less shifts in the aggregate supply schedule are taken into account. Consider Figure 8. Figure 8.13a, movements in output and price are caused by shifts in the aggregate deman curve(from y% to In this increases in price(from Po to P1, then to P, would be accompanied by increases in output to yi, en to y,). The demand ule shifts to the right along the fixed upward-sloping supply curve, increasing price and both output. Shifts to the left in the aggregate demand curve cause both output and price to fall. Therefore, shifts in the aggregate demand schedule do not provide an explanation for the be- havior of price and in years such as and 1980, when output fell but price rose, and in fact the rate price increase accelerated.