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


  • David O. Cushman


In early 2009, the incoming Obama administration’s Council of Economic Advisers predicted real GDP would rebound strongly from recession levels. In a blog post, Greg Mankiw expressed skepticism. In their blogs, Brad DeLong and Paul Krugman sighed. Of course there would be strong growth, they maintained, because the recovery of employment would mandate it via Okun’s Law. Mankiw challenged Krugman to a bet on the issue, but there was no response. Of course we now have a good idea of the likely outcome, but I posit a hypothetical time series econometrician who, at the time of the blog entries, applies some standard forecasting methods to see whether DeLong and Krugman’s confidence was justified. The econometrician’s conclusion is that Mankiw would likely win the bet and furthermore that a rebound of any significance is unlikely. The econometrician has no idea how DeLong and Krugman could have been so confident in the CEA’s rebound forecast.

Suggested Citation

  • David O. Cushman, 2012. "Mankiw vs. DeLong and Krugman on the CEA's Real GDP Forecasts in Early 2009: What Might a Time Series Econometrician Have Said?," Econ Journal Watch, Econ Journal Watch, vol. 9(3), pages 309-349, September.
  • Handle: RePEc:ejw:journl:v:9:y:2012:i:3:p:309-349

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    References listed on IDEAS

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    Cited by:

    1. Devereux, John & Dwyer, Gerald P., 2016. "What determines output losses after banking crises?," Journal of International Money and Finance, Elsevier, vol. 69(C), pages 69-94.
    2. Hosseinkouchack, Mehdi & Wolters, Maik H., 2013. "Do large recessions reduce output permanently?," Economics Letters, Elsevier, vol. 121(3), pages 516-519.
    3. Tolga Omay & Rangan Gupta & Giovanni Bonaccolto, 2017. "The US real GNP is trend-stationary after all," Applied Economics Letters, Taylor & Francis Journals, vol. 24(8), pages 510-514, May.
    4. repec:kap:revaec:v:30:y:2017:i:2:d:10.1007_s11138-016-0340-5 is not listed on IDEAS
    5. Athanassios Petralias & Sotirios Petros & Pródromos Prodromídis, 2013. "Greece in Recession: Economic predictions, mispredictions and policy implications," GreeSE – Hellenic Observatory Papers on Greece and Southeast Europe 75, Hellenic Observatory, LSE.

    More about this item


    Greg Mankiw; Brad DeLong; Paul Krugman; Council of Economic Advisers; real GDP; forecasts; ARIMA; VAR;

    JEL classification:

    • C53 - Mathematical and Quantitative Methods - - Econometric Modeling - - - Forecasting and Prediction Models; Simulation Methods
    • E37 - Macroeconomics and Monetary Economics - - Prices, Business Fluctuations, and Cycles - - - Forecasting and Simulation: Models and Applications
    • C22 - Mathematical and Quantitative Methods - - Single Equation Models; Single Variables - - - Time-Series Models; Dynamic Quantile Regressions; Dynamic Treatment Effect Models; Diffusion Processes


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