Inflation: Not Merely a Monetary Phenomenon

I’m a big fan of Milton Friedman. I’m also a big fan of easy-to-remember phrases that impart great wisdom. It honestly made me wince the first time I said the following:

Inflation is *not* everywhere and always a monetary phenomenon“.

The reasoning is as plain as day. Consider the quantity equation:

MV=PY

For the uninitiated, M is the money supply, V (velocity) is the average number of times dollars transacts during a period, P is the price level, and finally Y is real output during a period. This equation is often called the “equation of exchange” or “the quantity equation”. Strictly speaking, it is an identity. It is a truism that cannot be violated. All economists agree that the equation is true, though they may disagree on its usefulness.

Inflation is simply the percent change in price. We can rearrange the quantity equation, solving for price, in order to see the relationship between the price level and its determinants.

P= MV/Y

What does this mean? It means that more money results in more inflation, all else held constant. It means that higher velocity results in more inflation, all else held constant. It means that less output results in more inflation, all else held constant.

Why would Milton Friedman say that inflation is always caused by changes in the money supply if it is clear that there are two other causes of the price level? When Milton Friedman said his famous quote, output growth was relatively steady. Velocity growth was relatively steady. For his context, Milton Friedman was right. The majority of price and inflation volatility was found in changes in M. See below.

Strictly speaking however, Milton Friedman knew better and he knew that the statement was not strictly correct. Friedman was a public intellectual and he was a great simplifier. He taught many people many true things. At the time, people were blaming inflation on a great variety of things: taxes, fish catches, and unions, to name a few. Arguably, Friedman got them closer to the truth.

Now, there are economists that are pointing to total spending as the driver of inflation. After all, both sides of the equation of exchange describe NGDP (a.k.a. – Aggregate Demand or Aggregate Expenditure). Replacing M and V in the equation with NGDP yields:

P=NGDP/Y

What does this mean? It means that higher NGDP results in more inflation, all else held constant. It means that less output results in more inflation, all else held constant.

But economists dismissing M in lieu of AD are committing the same oversimplification. Y can also change! Maybe economists figure that our recent history is full of relatively stable Y growth and that we ought not pay attention to it. And indeed, unsurprisingly, RGDP growth has been less than NGDP growth.

But what is driving the current bought of inflation?

Pardon the crude image. The pink lines are eye-balled trend lines on natural logged data for AD, Y, and P. Prices are up. Is it because of exceptionally high NGDP? Nope. Total spending is back on pre-2020 trend. Does Y happen to be down? Yep, it sure is.

Right now, assuming the previous trend was anywhere close to potential output, inflation is not being driven by excess aggregate demand. It’s being driven by inadequate real output. The news tells the story. There have been supply-chain bottle-necks, difficulty employing, lockdowns, and fear of covid. Right now we have an output problem and higher prices are a symptom. We do not have an aggregate spending problem.

PS – In fact, it is my belief that the Fed successfully avoided a debt-deflation aggregate demand tumble that would have been catastrophic. Inflation is expected when supplies of goods decline.

Why Do We Care About Inflation?

The title question may seem obvious. “We” care about inflation because, ultimately, any dollars we have saved will purchase fewer real goods and services. Additionally, we might worry that our incomes are not keeping pace with the increase in the prices of good and services that we want to purchase.

But the answer to that question is a little more nuanced. “We” also care about why prices are increasing. I keep putting “we” in quotation marks because who the we is crucial for answering the question. For example, individuals and families primarily care about inflation for the reasons I stated in the first paragraph.

But central bankers care about inflation for different reasons. In broad terms, monetary policy is an attempt to smooth out the fluctuations in the economy, especially to make recessions shorter and less deep. But monetary officials want to know: is the policy they are putting in place leading to prices rising in general? If so, especially if inflation gets above certain target levels, it may mean that monetary has been “too loose.”

However, if particular prices are rising, say the price of cars (due to a lack of computer chips), central bankers don’t really care about this: it gives them no indication of whether they’ve done “too much” or “too little” with regards to stimulating the economy. Similarly, if gasoline prices rise, consumers really care about this. Central bankers, not so much: it doesn’t really tell them much about their goal (stimulating the economy with stimulating it too much).

And because some prices are so volatile, historical context is important for understanding what a recent increase or decrease means. For example, gasoline prices are up 45% in the past 12 months. That’s a lot! But it’s an increase from a very low base, and the historical reality is that gasoline prices today (around $3.00/gallon on average) are at similar levels to what they were way back in 2006, and are lower than they were for almost all of 2011-2014. And these are all in nominal terms, median household income has gone up a lot since 2006 (up 40% in nominal terms) and even since 2014 (up 25%).

All of this is important background for thinking about the latest release of the CPI-U data this week. The headline inflation number of 5.3% is indeed startling, similar to last month. We haven’t touched that level since mid-2008, and that was only for a few months. If consumer price inflation were to stay at around 5% for a sustained period of time, it would be a new, harsh reality for most consumers today: we haven’t had a year with 5% inflation since 1990, and for the past decade the average has hung around 2%.

So will it stay this high? Sadly, I have no crystal ball and I will just reiterate what I said last month: the picture is just too muddled right now to say anything concrete. Perhaps by the end of the year we will have a better picture. But is there anything we can say right now even with the muddled picture? I continue to like this chart from the Council of Economic Advisors:

Image

Bottom line: if we strip out the unusual supply chain disruptions to automobiles as well as airline/hotel prices making up for lost ground during the pandemic, inflation is at completely normal levels. It’s almost exactly 2%

But is this cheating? Can we really strip out the things that are increasing at rapid rates?

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Penny-Pinchers Gonna Pinch

Text books say that there are two major problems with the Consumer Price Index (CPI). First, accounting for changes in quality is difficult. Second, the CPI is calculated by assuming a fixed basket of goods is consumed over time. For both of these reasons, the rate of inflation that is implied by CPI is typically considered to be about 1% overestimated.

Imperfectly accounting for quality improvements causes higher measured inflation because the stream of services that a product creates for the consumer has increased – even though the product is nominally the same product. For example, the camera on my smart-phone is now good enough to record a high-quality Youtube video, whereas it was of mediocre quality on my previous phone.  My life is better-off with the better camera. But the increase in my quality of life isn’t measured by the CPI. The CPI does, however, make note that I paid a higher price for a phone.

Further, people don’t consume a fixed basket of goods over time. Even if we stopped the introduction of all new products and maintained the quality of all current products, people would still change the composition of their consumption due to price changes among related goods.

When people get hot and bothered by inflation, they often appeal to people who are of less means and who would find higher prices more burdensome. For that reason, below is a graph of some calorically dense and roughly comparable food staple prices (from the PPI).  You can put a protein on top of any one of these and call it a meal: pasta, flour, potatoes, & rice.

Let’s say that a consumer consumed equal parts of these in January of 2020. The CPI assumes that the consumption basket remains constant and plots a weighted average. In such a case, price rose 2.3% through July 2021. But in real life, penny-pinchers gonna pinch. If our consumer is particularly Spartan, then he will always consume the cheapest option – he treats the different foods as perfect substitutes. The Spartan price of consuming *fell* 22.3%. To be clear, the CPI assumes that the consumption composition remains unchanged, while the consumer’s actual basket is responsive to price changes.  Even if a consumer considers these goods to be imperfect substitutes and is willing to cut any particular type of consumption in half in favor of the cheapest alternative, then the price fell by 10%. In fact, a consumer who is at all responsive to prices will always have a cheaper basket than the headline CPI, all else constant.

In conclusion, be careful with your money. Spend it well and seek out alternatives. Your flexibility determines how much money you’ll have at the end of the month. The headline CPI number impacts only the most passive consumer – and even then, budget constraints gonna constrain.

Beer, Hot Dogs, and Inflation

The latest inflation data for the US has been released, and the headline CPI-U annual increase of 5.4% is once again raising worries that high inflation could be a permanent part of the landscape for the near future.

My personal opinion is that the picture is much too muddled now, between temporary supply issues and low bases for 2020 prices, to say much about the medium-term picture. I think we’ll have a better picture by the end of the year. Still, it’s worth drilling down into the data, as we have done in the past on this blog, to understand some things about economics, prices, and how price changes are impacting real people.

Certainly the prices of some goods are rising at alarming rates. Many of these are related to automobiles and transportation generally, but some categories of food have rose a lot in the past year too (though groceries overall are only up 2.6%).

But I want to talk about two categories of consumption: beer and hot dogs.

Actually, my co-blogger Zachary has already written about beer. And using the producer price index, he found that canned beer is actually cheaper than it was a year ago. If you like canned beer, rejoice! And for all beer at home, the CPI shows only a 1.8% increase since last year, after a similar small 1.6% increase last July (not much of a base effect… a clue for later!).

But not all Americans consumer alcohol. So let’s talk about that most American food product: the hot dog.

Why should we care about hot dogs? Read on.

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A Canned-Beer Kind of Guy

An  ex-co-worker was once complaining to me that the prices of things that he liked kept going up.

He was an economics major. Of course he knew that wages also increase. He wasn’t simply cantankerous about inflation. He knew all about improving productivity, income, and price level changes. He was being more specific. The *particular* items that *he* liked were getting more expensive. He was complaining about what, to everyone else, were relative price changes.

Unrelatedly, I was floating around the bls.gov website and examining their Producer Price Index (PPI) FAQs (I learned a bunch). The content is extensive. CPI is broken up into some subcategories. But PPI, being used by multiple industries and trade groups for real-life costs and benefits, is excitingly granular.

You want to know what happened to the price of red, white, rose, and carbonated wines each in particular?  They’ve got you covered. It really is amazing.

Back to my co-worker. I tried to explain that relative price changes reflected underlying economic value and scarcities. We wasn’t having any of it. He just didn’t want his prices to go up. We economists are known for being kind of dispassionate. We see relative prices change and we shrug. Man-on-the-street sees a relative price change and, boy, does he care about it – if it’s the purchasing price that *he* faces.

See the below graph. What kind of consumer are you? Since the start of the pandemic, canned, bottled, and kegged beer have all changed in price. Or maybe you’re a teetotaler and you’ve noticed the increasing price of bottled water.  For interpretability, let’s consider what had cost $10 at the start of the year 2020. Bottled water has gone up to $10.50 and bottled beer has gone up to almost $10.30.  You may not blink at a 3% price increase – unless it’s for 6 bottles of your favorite craft beer.

The price of canned beer, on the other hand, hardly increased at all. And in the last couple of months, the price *fell*. I sure hope that my co-worker is a canned-beer kind of guy. Otherwise, someone is sure to hear a lot of belly-aching.

Flying the Friendly Skies (Today and in the Past)

It’s almost summer. About half the US population has at least one dose of a COVID vaccine. For many Americans that haven’t had their employment impacted by the pandemic, their bank accounts are flush with cash and they are ready to do one thing with that cash: travel. See family and friends. See something other than the inside of your own home.

And for many Americans traveling this summer, they will fly. The airlines, no doubt, will appreciate your business. At this time last year, the world had so radically shifted that Zoom’s market cap was bigger than the 7 largest airlines in the world. In May 2020, air passenger traffic in the US was less than 10% of traffic in 2019. Today, we’ve recovered a lot, but we are still only back to about two-thirds of normal levels. And since airplanes are just a marginal cost with wings, flying all their planes at close to full capacity is crucial for airlines to return to profitability. They really need you to fly the friendly skies this summer.

One of the reasons that so many Americans are able to fly in today is because flying is, compared to historical prices, very cheap.

How cheap is flying to today compared to the past? Let’s look at some historical price data for flights.

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The Pappy Pricing Puzzle

If you drink bourbon whiskey (or even if you don’t) you’ve probably heard of Pappy Van Winkle. Bourbon has experienced something of a revival in the past two decades, after being in decline for much of the 20th century. As part of this revival, some bourbons have become very highly sought after by the nouveau bourbon enthusiasts. And the various offerings of Pappy Van Winkle are arguably the most highly sought after. Finding Pappy is almost impossible these days, though this was also true a decade ago so it’s not really a “new” phenomena.

So here’s the “puzzle” for economists: why aren’t Pappy and other rare whiskies sold at market prices? No one in the “legal” market seems willing to do so. I put “legal” in quotation marks because there is a robust secondary market for these bottles, and the legal status of these sales is entirely unclear to me as an economist (alcohol markets are, to say the least, highly regulated).

In these secondary markets, it is not unusual for a 20-year bottle of Pappy Van Winkle to sell for $2,000. The “manufacturer’s suggested retail price” is $199.99. But you will never find this bottle on the shelf for that price. The bottles are held by retailers, either to sell to friends, auction off for charity, or conduct a lottery for the right to purchase the bottle at well below market prices.

So why doesn’t the distillery raise the MSRP? Clearly, they do this from time to time. Ten years ago, if you were lucky enough to find this bottle it was around $100 (I was lucky enough, on occasion). Clearly, they recognize that prices can increase. And that’s not just “keeping up with inflation”: $100 in 2011 is about $120 in current dollars. By 2016, they had raised the MSRP to $169.99. But why doesn’t the distillery raise the price more, perhaps all the way up to the market clearing price? By doing so, they would, perhaps, be able to ramp up production so that in 2041 there might be a lot more Pappy on the shelf. At the very least, they could dramatically increase their profit.

Receipt for 1 bottle of 20-year Pappy and 2 bottles of 12-year Van Winkle “Special Reserve” from 2011.

Also, why don’t retailers just put bottles on the shelf at $2,000? Stores occasionally do this, but mostly because they are fed up with all of the customers calling about rare bottles. Sometimes they will price it even higher than secondary markets. But usually, they allocate the bottles by something other than the price mechanism. Why? Businesses don’t usually leave dollar bills, especially $1,000 dollar bills, on the table.

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Hyperinflationary Efficiency?

I’m advising a senior thesis for a student who is examining the strength of Purchasing Power Parity in hyper-inflationary countries. Beautifully, the results are consistent with another author* who uses a more sophisticated method.

For those who don’t know, absolute purchasing power parity (PPP) depends on arbitrage among traders to cause a unit of currency to have the same ability to acquire goods in two different countries. If after converting your currency you can afford more stuff in foreign country, then there is a profit opportunity to purchase there and even to re-sell it in your home country.

Essentially, when you make that decision, you are reducing demand for the good in your home country and increasing demand in the foreign country (re-selling affects the domestic supply too). Eventually, the changes in demand cause the prices to converge and the arbitrage opportunities disappear. At this point the two currencies are said to have purchasing power parity – it doesn’t matter where you purchase the good.

So does PPP hold? One way that economists measure the strength of PPP is by measuring the time that it takes for a typical purchasing power difference to be arbitraged away by 50% – its ‘half-life’.  The more time that is required, the less efficient the markets are said to be.

The ex-ante question is: Is PPP be stronger or weaker during hyperinflationary periods?

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