Covid Evidence: Supply Vs Demand Shock

By the time most students exit undergrad, they get acquainted with the Aggregate Supply – Aggregate Demand model. I think that this model is so important that my Principles of Macro class spends twice the amount of time on it as on any other topic. The model is nice because it uses the familiar tools of Supply & Demand and throws a macro twist on them. Below is a graph of the short-run AS-AD model.

Quick primer: The AD curve increases to the right and decreases to the left. The Federal Reserve and Federal government can both affect AD by increasing or decreasing total spending in the economy. Economists differ on the circumstances in which one authority is more relevant than another.

The AS curve reflects inflation expectations, short-run productivity (intercept), and nominal rigidity (slope). If inflation expectations rise, then the AS curve shifts up vertically. If there is transitory decline in productivity, then it shifts up vertically and left horizontally.

Nominal rigidity refers to the total spending elasticity of the quantity produced. In laymen’s terms, nominal rigidity describes how production changes when there is a short-run increase in total spending. The figure above displays 3 possible SR-AS’s. AS0 reflects that firms will simply produce more when there is greater spending and they will not raise their prices. AS2 reflects that producers mostly raise prices and increase output only somewhat. AS1 is an intermediate case. One of the things that determines nominal rigidity is how accurate the inflation expectations are. The more accurate the inflation expectations, the more vertical the SR-AS curve appears.*

The AS-AD model has many of the typical S&D features. The initial equilibrium is the intersection between the original AS and AD curves. There is a price and quantity implication when one of the curves move. An increase in AD results in some combination of higher prices and greater output – depending on nominal rigidities. An increase in the SR-AS curve results in some combination of lower prices and higher output – depending on the slope of aggregate demand.

Of course, the real world is complicated – sometimes multiple shocks occur and multiple curves move simultaneously. If that is the case, then we can simply say which curve ‘moved more’. We should also expect that the long-run productive capacity of the economy increased over the past two years, say due to technological improvements, such that the new equilibrium output is several percentage points to the right. We can’t observe the AD and AS curves directly, but we can observe their results.

The big questions are:

  1. What happened during and after the 2020 recession?
  2. Was there more than one shock?
  3. When did any shocks occur?

Below is a graph of real consumption and consumption prices as a percent of the business cycle peak in February prior to the recession (See this post that I did last week exploring the real side only). What can we tell from this figure?

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Primary Driver for This Inflation Is Surging Demand (Fueled by COVID Payments), Not Supply Chain Constraints

Inflation is colloquially defined as, “Too much money chasing too few goods (and services)”. Supply chain constraints get talked about, and these are widely blamed for the inflation we are seeing.  Of course, supply limitations play into inflation, but to focus on them is to miss the elephant in room. The primary driver of this inflation is not “too few goods”, but “too much money.”

Such is the thesis of a widely circulated article by Ray Dalio’s investing firm Bridgewater Associates, “It’s Mostly a Demand Shock, Not a Supply Shock, and It’s Everywhere.” The point is summarized:

While the headlines tend to focus on the micro elements of the supply shock (the LA port, coal in China, natural gas in Europe, semiconductors globally, truckers in the UK, etc.), this perspective largely misses the macro cause that is likely to persist and for which there is no idiosyncratic solution. This is not, by and large, a pandemic-related supply problem: as we’ll show, supply of almost everything is at all-time highs. Rather, this is mostly an MP3-driven upward demand shock. [emphases in the original]

In Bridgewater’s terminology, “MP3” is “Monetary Policy #3”, and refers to massive deficit spending combined with central bank quantitative easing. We saw this implemented in 2020-2021 when the federal government pumped out trillions of dollars of stimulus payments and enhanced unemployment benefits, and the Fed instantly soaked up the bonds that were issued to pay for these trillions. This fed/Fed combo amounts to simply printing money on an enormous scale.

Those trillions of dollars funded a huge surge in durable goods purchases. By late 2021 the supply of these goods was well above 2019 (pre-COVID) levels, and even above normal growth trendlines. However, the supply and transport systems simply could not grow fast enough to accommodate this insatiable demand. Charts below substantiate this. To focus on supply chain bottlenecks of themselves is misleading. The primary driver for this inflation has been the trillions of dollars of federal largesse. The Fed knows all this, obviously, but Jay Powell (the Chief Enabler of this deficit spending) would likely not have been reappointed if he spoke too directly about the cause of this inflation. Hence the endless prattle about supply chains.

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