Journaltalk - Mankiw vs. DeLong and Krugman on the CEA’s Real GDP Forecasts in Early 2009: What Might a Time Series Econometrician Have Said?

Mankiw vs. DeLong and Krugman on the CEA’s Real GDP Forecasts in Early 2009: What Might a Time Series Econometrician Have Said?

About this article

  • David O. Cushman
Keywords Greg Mankiw, Brad DeLong, Paul Krugman, Council of Economic Advisers, real GDP, forecasts, ARIMA, VAR
Volume Number 9
Issue Number 3
Pages 309-349
File URL Mankiw vs. DeLong and Krugman on the CEA’s Real GDP Forecasts in Early 2009: What Might a Time Series Econometrician Have Said?
Publication year 2012

Flag this article

Flag this article for moderation.

Close this.

About Econ Journal Watch

Grouping social sciences
Categories economic, economics

Flag this journal

Flag this journal for moderation.

Close this.

Add a comment to this discussion.


  1. As a non-economist, I lack the expertise to critique the methodology of an economic analysis of this sort, but I’m skeptical of the objectivity of a hypothetical, retrospective prediction of what is now known to have transpired since. Why “posit a hypothetical time series econometrician who, at the time of the blog entries, applies some standard forecasting methods”? Weren’t such analyses with these “standard forecasting methods” done at the time? Did Professor Cushman offer such an analysis at the time?

    posted 23 Sep 2012 by Brooks

  2. Krugman has responded to this article with:
    I guess I should take it as a compliment that people who want to attack my record feel the need to make stuff up.

    posted 24 Sep 2012 by Frank Nospam

  3. Oh, please, please, please give us a link to where Paul Krugman said the 2009 stimulus was going to lead to “strong growth”.

    (And if you are unable to, does that mean you are, as Krugman contends, making it up?

    posted 24 Sep 2012 by John Quick

  4. The article misreads Krugman’s comments. In the blog entry the article cites (, Prof. Krugman makes a technical argument against Mankiw’s use of the unit root in his analysis. He does not make a prediction about the speed of the recovery. Krugman’s articles around the time had made it clear that he thought the recession would be deep and the stimulus too small and that the Obama administration was setting itself up for problems in the future by underestimating what needed to be done.

    I will include the full text below:

    March 3, 2009, 9:06 PM
    Roots of evil (wonkish)
    As Brad DeLong says, sigh. Greg Mankiw challenges the administration’s prediction of relatively fast growth a few years from now on the basis that real GDP may have a unit root — that is, there’s no tendency for bad years to be offset by good years later.

    I always thought the unit root thing involved a bit of deliberate obtuseness — it involved pretending that you didn’t know the difference between, say, low GDP growth due to a productivity slowdown like the one that happened from 1973 to 1995, on one side, and low GDP growth due to a severe recession. For one thing is very clear: variables that measure the use of resources, like unemployment or capacity utilization, do NOT have unit roots: when unemployment is high, it tends to fall. And together with Okun’s law, this says that yes, it is right to expect high growth in future if the economy is depressed now.

    But to invoke the unit root thing to disparage growth forecasts now involves more than a bit of deliberate obtuseness. How can you fail to acknowledge that there’s huge slack capacity in the economy right now? And yes, we can expect fast growth if and when that capacity comes back into use.

    posted 24 Sep 2012 by Chris Lee-Messer

  5. And which econometrician will regard this blatant misrepresentation of the facts as proof that the economics profession has been hijacked by corporate speaking engagement fees and simplistic right wingers who have a criticism for everything, but reverence for only the practice of doing less (so the ‘free market’ can work its magic, don’t you see?) I really hope the state of economics improves to the point where people like Cushman and Mankiw will be held to account for their lies, but remembering Nial Ferguson’s hack journalism in Newsweek reminds me that their are lots more inane fact manipulating liars to go through first. Oh yeah, and Phil Gramm has something to say about the economy in the WSJ. I assume its not that we are still in a “mental recession” as this “nation of whiners” was in 2008? Jeez, the fact these people even get writing gigs anymore makes me want to steal things from 7 eleven.

    posted 24 Sep 2012 by Alex Nash

Log in to Journaltalk to discuss this article!

Don’t have a Journaltools account? Sign up now.


Log in to Your Account

Member login

feed Jt Article Discussions

31 Mar

Christianity Changes the Conditions of Government
Trygve Hoff's Appeal to Ragnar Frisch: Four Letters from 1941
Classical Liberal Think Tanks in Greece, 1974–2024
Classical Liberalism in Russia
Revisiting Hypothesis Testing with the Sharpe Ratio
What Is the False Discovery Rate in Empirical Research?
Journaltalk: Opening the journals to civil voices everywhere!

All contents © 2024 by Daniel Klein unless otherwise attributed. All rights reserved.