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Keynesian AD/AS diagram confusion


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In my economic textbook, it separates  the Aggregate Supply curve into LRAS, which is a vertical line, and SRAS, which is a curve. However, I buy a guidebook of IB economics, inside, it says the AS is only one line, which is demonstrated as a curve, without the vertical line; also they did not separate into two components, long run and short run. So which one is the correct version of the Keynesian model?

 Image result for keynesian ad as model Image result for keynesian ad as model

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On 2016/10/16 at 1:28 AM, Genri said:

the second diagram is the long run Keynesian model and the first diagram, the vertical line,  is the long run monetarist model. 

for the SR, all the curves are basically diagonals, just like the normal supply curve  

 

But why they put a monetarist LRAS inside graph one, whereas label the curve, similar to Keynesian LRAS, as SRAS? 

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12 hours ago, Throne said:

But why they put a monetarist LRAS inside graph one, whereas label the curve, similar to Keynesian LRAS, as SRAS? 

The second diagram shows the ADAS model from the Keynesian perspective, which consists of the Keynesian AS curve which is perfectly inelastic at low levels of output, and moves to become perfectly inelastic beyond the full employment level of output, Yf. So, the second diagram is a correct representation of the Keynesian model. 

The first diagram shows the ADAS model from the New Classical perspective. It consists of a vertical LRAS curve at Yf, and the AD and SRAS curves. Although the SRAS curve in the diagram you provided is shaped like the Keynesian AS, you should not mistake them to be the same thing - you can very well illustrate the SRAS as a straight diagonal line instead (as in the diagram below). In fact, drawing the SRAS as a diagonal is what's in most IB economics text books. 

 

 

Screen Shot 2016-10-20 at 4.31.52 pm.png

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37 minutes ago, Natasha said:

The second diagram shows the ADAS model from the Keynesian perspective, which consists of the Keynesian AS curve which is perfectly inelastic at low levels of output, and moves to become perfectly inelastic beyond the full employment level of output, Yf. So, the second diagram is a correct representation of the Keynesian model. 

The first diagram shows the ADAS model from the New Classical perspective. It consists of a vertical LRAS curve at Yf, and the AD and SRAS curves. Although the SRAS curve in the diagram you provided is shaped like the Keynesian AS, you should not mistake them to be the same thing - you can very well illustrate the SRAS as a straight diagonal line instead (as in the diagram below). In fact, drawing the SRAS as a diagonal is what's in most IB economics text books. 

 

 

 

So, does this mean that Keynesian ADAS diagram does not need to distinguish between short run and long run? 

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