Demand Shocks and Real GDP Measurement

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28 Οκτ 2013 (πριν από 4 χρόνια και 13 μέρες)

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Demand Shocks

and Real GDP Measurement


by Emi Nakamura

Discussion by Susanto Basu

Comments on

SSHRC Conference, Vancouver, June 29, 2004

Demand & Real GDP

CRIW Conference, June 29, 2004

2

The really quick summary

S

D

S’

D’

Q
0

P
0

Q
1

Demand & Real GDP

CRIW Conference, June 29, 2004

3

Index number theorist’s reaction


This is a novel and striking result


Also very simple

once explained!


Explains some puzzling facts


Demand shocks create interpretation problems for
Fisher and Paasche indices


But can attach an utility
-
based interpretation to
Laspeyres index




Demand & Real GDP

CRIW Conference, June 29, 2004

4

Macroeconomist’s reaction


One more reason to not attach a structural
interpretation to real GDP


Are problems worse than, e.g., aggregation across
consumers with differing MU’s of wealth?


Macroeconomists will ignore measurement issues
unless they matter for particular applications


Needed: Example(s) where macroeconomists will
draw wrong/misleading conclusions by using chain
-
weighted real GDP when there are demand shocks

Demand & Real GDP

CRIW Conference, June 29, 2004

5

One example of a macro application*


In a multi
-
sector economy, suppose a transitory, persistent
technology improvement in, say, sector 1 raises Q
1
(t) by X(t)


Now suppose instead a transitory demand shock that has the
same effect on the time path of Q
1
(t)


The increase in total GDP due to the technology shock will
appear smaller (because P
1

falls), but will also appear more
persistent

since P
1

is rising as the shock fades away


By contrast, the demand shock will appear less persistent,
because GDP will rise by more on impact (since P
1

will rise with
Q
1
), but then also fade away more quickly, since P
1

will fall as
Q
1

asymptotes back to zero.


Thus the persistence of GDP, which is of great interest to
macroeconomists, depends on the type of shocks


* Inspired by a comment from Carol Corrado