Chapter 22 The second section in Chapter 23 contains one of the most important factors studied in chapter. This section in the textbook (on pages 566 to 571) carefully explains the difference between the short-run aggregate supply curve (SAS) and the long-run aggregate supply curve (LAS). The difference between these two curves is one of the most important points examined in the chapter because it shows how a change in aggregate demand has different short-run and long-run effects. We see in more detail in later chapters how the government attempts to influence the nation's economic condition by changing aggregate demand. Therefore the result that the long run effect differs from the short-run effect can assume immense importance. The figure on this page, like the similar figures in the text, shows both the short-run aggregate supply curve (labelled SAS) and long-run aggregate supply curve (labelled LAS). The difference between these two curves is immediately apparent: The short-run aggregate supply curve is upward sloping while the long-run aggregate supply curve is vertical. What accounts for this difference? To find out, click on one of the figures below.