Four missing ingredients in macroeconomic models

It is refreshing to see top academics questioning some of the assumptions that economists have been using in their models. Krugman, Brad DeLong and many others are opening a methodological debate about what constitute an acceptable economic model and how to validate its predictions. The role of micro foundations, the existence of a natural state towards the economy gravitates,... are all very interesting debates that tend to be ignored (or assumed away) in academic research.

I would like to go further and add a few items to their list that I wished could become part of the mainstream modeling in economics. In random order:

1. The business cycle is not symmetric. Most macroeconomic models start with the idea that fluctuations are caused by a succession of events that are both positive and negative (on average they are equal to zero). Not only this is a wrong representation of economic shocks but is also leads to the perception that stabilization policy cannot do much. Interestingly, it was Milton Friedman who put forward the "plucking" model of business cycles as an alternative to the notion that fluctuations are symmetric. In Friedman's model output can only be below potential or maximum. If we were to rely on asymmetric models of the business cycle, our views on potential output and the natural rate of unemployment would be radically different. We would not be rewriting history to claim that in 2007 GDP was above potential in most OECD economies and we would not be arguing that the natural unemployment rate in Souther Europe is very close to its actual.

2. As much as the NBER methodology emphasizes the notion of recessions (which, by the way, is asymmetric in nature), most academic research is produced around models where small and frequent shocks drive economic fluctuations, as opposed to large and infrequent events. The disconnect comes probably from the fact that it is so much easier to write models with small and frequent shocks than having to define a (stochastic?) process for large events. It gets even worse if one thinks that recessions are caused by the dynamics generated during expansions. Most economic models rely on unexpected events to generate crisis, and not on the internal dynamics that precede the crisis.

[A little bit of self-promotion: my paper with Ilian Mihov on the shape and length of recoveries presents some evidence in favor of these two hypothesis.]

3. There has to be more than price rigidity. Keynesian models rely on price rigidity to explain business cycles and why demand matters. There is plenty of evidence that price rigidities are important and they help us understand some of the features of the business cycle. But there must be more than that. There are other frictions in the real economy that produce a slow adjustment and are responsible for the persistence of business cycles. They might not be easy to measure or model, they might be different across different economies but it is difficult to imagine that an adjustment of prices and wages to its optimal level would automatically restore full employment. Larry Summers referred to these frictions in his recent IMF conference speech although he did not elaborate on them.

4. The notion that co-ordination across economic agents matters to explain the dynamics of business cycles receives very limited attention in academic research. It some times appear in our economic policy debate (e.g. Olivier Blanchard (at the IMF) has referred to multiple equilibria as a way to explain the sovereign-debt crisis in Europe) but it does nor receive the credibility it deserves in academia.

I am aware that they are plenty of papers that deal with these four issues, some of them published in the best academic journals. But most of these papers are not mainstream. Most economists are sympathetic to these assumption but avoid writing papers using them because they are afraid they will be told that their assumptions are ad-hoc and that the model does not have enough micro foundations (for the best criticism of this argument, read the latest post of Simon Wren-Lewis). Time for a change?

Antonio Fatás

Debt and secular stagnation

In a recent post Paul Krugman refers to the potential link between rising levels of debt prior to the 2008 crisis and the current discussion on secular stagnation. The argument can be illustrated by the chart below (borrowed from Krugman's post).

Quoting from Krugman's post: 

"Debt was rising by around 2 percent of GDP annually; that's not going to happen in the future, which a naive calculation suggests a reduction in demand, other things equal, of around 2 percent of GDP"

In summary, increasing debt ratios area unsustainable and the adjustment can have a negative effect on growth. The argument is probably right but when it comes to assessing the real impact on growth I think we need to do a more careful analysis before reaching that conclusion. 

Here is where I think the reading of the previous chart becomes more complicated: Why was debt going up? For some this is simply a reflection of excessive spending that directly feeds into demand. The fact that it is excessive leads to the need to reverse the trend in the years that follow and, using the same logic but now going back, it will lead to a reduction in demand. But to reach that conclusion we first need to do a more careful analysis of the balance sheet of US households by looking not only at their liabilities but also at their assets. Below is a chart of total assets (blue line) and just financial assets (red line) during the same period of time (and both measured as % of GDP).

We also observe an upward trend. How do these two trends (assets and liabilities) compare? We can measure it by looking at the difference between assets and liabilities = net wealth of US households (as % of GDP).

What we see is also an upward trend with large volatility around the last two recessions. An upward trend means that asset values are growing faster than debt. Today's net wealth is below the peak of 2005-2006 but it is above the level of any other year in the sample. With this new perspective it is more difficult to conclude that debt is still high or that it cannot grow from current levels. 

What I find more interesting (and intriguing) is that rising debt (as a % of GDP) at the same time as asset values increase (even faster) is not the exception but the norm when one looks at a larger sample. 

Below is the evolution of Household Debt (blue, right axis) and Net Worth (red, left axis), both as % of GDP during the 1975-1995 period. So I am excluding the last two asset price bubbles to look at a more "normal" period. We still see rising trends for both series. So debt ratios were increasing fast but asset values were growing at an even faster rate, so the net worth kept going up through those 20 years.

What these charts suggest is that the analysis of debt is a complex one and it requires a careful look at both sides of the balance sheet. And unless I am missing some relevant academic research, we do not have a good framework to think about these trends. And things can get a lot more complicated if we start adding other issues, such as the distribution of holdings of assets and liabilities. It could be that the households that are holding the assets are not be the same as the ones holding the debt, and this can change the way we think about the implications of these trends.

Antonio Fatás

Battle lost: austerity won.

It has been surprising to see how over the last five years some have been holding to their economic theories even if the facts kept proving them wrong (Yyperinflation? Confidence and austerity?). At the end, it seems that ideology dominates much of the macroeconomic analysis we see these days. But what is more surprising is how broad this phenomenon is and how the general economic commentary that one reads in the press cannot move away from those theories either.

One statement that will not go away is the constant reference to "printing money" which is not only incorrect from a factual point of view (most of the increase in the monetary base corresponds to reserves not to bank notes being printed) but also misleading when it comes to the understanding of the role of central banks. Even those who support central bank actions during the crisis have to add a sentence at the end to warn us about the danger of so much liquidity.

And austerity, as much as the data has disproven the claim that it would be through reduction in government spending and increased confidence that advanced economies will return to healthy growth rates, it does not seem to lose its appeal either. As an example, here is a CNBC article that provides a long list of arguments of why austerity is winning the war. The arguments: the UK is finally growing, Spain's GDP is not falling anymore and even in Greece we now start seeing the possibility of positive growth. And where is this coming from? From the austerity that these wise governments have implemented over the last year. This is, of course, a misleading analysis of the data. It is still the case that countries where austerity was the strongest have seen the lowest growth rates (and the largest increase in debt). The only reason why these three countries are either returning to growth or not collapsing anymore is that after such a deep crisis, growth must return at some point. Yes, even without any policy actions to support growth, economies recover. But they do so slowly and they will never return to where they should have been. And just to get the facts straight, in these three countries, governments have stopped being a large drag in the economy. When you reduce government spending growth suffers. Once government has stabilized at a low level it does not become a drag on growth.

The last five years have provided an incredible macroeconomic experiments to learn about the effects of monetary and fiscal policy to stabilize cycles. But it seems that this crisis will be wasted, not so much in terms of implementing reforms but in terms of our ability to use data to improve our understanding of macroeconomics.

Antonio Fatás

Where did the saving glut go?

I have written before about the investment dearth that took place in advanced economies at the same time that we witnessed a global saving glut as illustrated in the chart below. In particular, the 2002-2007 expansion saw lower investment rates than any of the previous two expansions.

If one thinks about a simple demand/supply framework using the saving (supply) and investment (demand) curves, this means that the investment curve for these countries must have shifted inwards at the same time that world interest rates were coming down.

But what about emerging markets? Emerging markets' investment did not fall during the last 10 years, to the contrary it accelerated very fast after 2000.

This is more what one would expect as a reaction to the global saving glut. The additional saving must be going somewhere (saving must equal investment in the world). As interest rates are coming down, emerging markets engage in more investment (whether this is simply a move along a downward-slopping investment curve or a shift of the investment opportunities for any given level of interest rates is impossible to tell from this simple analysis).

We can also look at the world as whole

Starting in the year 2000 we see a trend towards higher investment driven by emerging markets. 

In equilibrium, both saving and investment have to move by the same amount (at the global level) so how do we know that this is a saving glut and not an increase in investment opportunities? The fact that interest rates were declining during these years means that these changes were dominated by an outward shift in the saving curve (if it had been investment shifting we would have seen interest rates increased). The resulting lower interest rates led to higher investment in emerging markets, as expected, but they did not foster any additional investment in advanced economies signaling that there has been a decline in investment opportunities in these countries. Whether this is a sign of a structural weakness that affects the inability of advanced economies to keep innovating at the same rate or purely a reflection of other, possibly cyclical, factors remains an open question.

Antonio Fatás

P.S. All data used to produce the charts above comes from the IMF World Economic Outlook. Individual country data has been aggregated using PPP GDP weights (using market exchange rates GDP weights provides very similar insights).