The International Monetary Fund launched a mea culpa operation a few months ago as it sought to clean up its reputation and record the "lessons learned" from its involvement in the euro-zone crisis.

The process started with a research paper on so-called fiscal multipliers, which measure the effects of cuts in public spending on a country's gross domestic product. As it turned out, the ones used to predict the effects of austerity on the euro zone's troubled economies were a tad optimistic.

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