9. The short-run aggregate supply curve (SRAS) based on the misperceptions theory slopes upward in describing the relation between out- put and the actual price level, with the expected price level held constant. In the long run, the price level equals the expected price level so that the supply of output equals Y; thus, the long-run aggregate supply curve (LRAS) is a vertical line at the point where output equals Y. In Chapter 12, we will see that an upward-sloping SRAS also summarizes the implications of the way in which Keynesian economists understand how output can vary from the full-employment level. While the explanations that Keynesians offer for the upward slope of the SRAS curve will differ from that offered by the mispercep- tions theory, the shape of the curve and the fac- tors that cause it to shift will be the same.