Your Grocery Shopping Shapes Your Inflation Expectations

Your Grocery Shopping Shapes Your Inflation Expectations

You know that feeling when you walk out of the grocery store and your receipt is twenty dollars more than it was last month? You chalk it up to the price of eggs, or maybe that fancy olive oil you bought. But here’s the thing: that feeling, that specific sting of a higher price on something you buy often, is not just a personal annoyance. It is a force that shapes the entire economy.

A 2019 study by Francesco D’Acunto, Ulrike Malmendier, Juan J. Ospina, and Michael Weber shows that the price changes you personally observe while shopping are a primary driver of your expectations for overall inflation (D’Acunto et al., 2019). Not the official Consumer Price Index. Not what the Federal Reserve says. But the price of milk, bread, and toothpaste. And because your inflation expectations influence your spending, saving, and borrowing decisions, central banks that ignore what you see in the checkout line might be making systematic mistakes.

Why Your Toothpaste Matters More Than Your Rent

The authors had an unusual data advantage. They used the Nielsen Homescan Panel, a dataset that tracks the actual grocery purchases of tens of thousands of U.S. households over years. For each household, they could see exactly what was bought, how much was paid, and how often that item was purchased. This allowed them to construct a household-level measure of perceived inflation: the price changes each individual actually experienced in their own shopping basket.

The finding was sharp. Perceived price changes helped explain inflation expectations across different people and within the same person over time (D’Acunto et al., 2019). In other words, if you saw the price of coffee jump by 10 percent last month, you were more likely to tell a survey that you expected overall inflation to be high. If your neighbor, who buys less coffee, saw no change, she would have lower expectations.

But the authors uncovered a more surprising twist. The frequency of a purchase, not how much you spend on it, is what makes a price change stick in your brain.

Think about it. You buy milk every week. You might spend $5. You renew your car insurance once every six months. You spend $600. Which price change matters more for your inflation expectations? The milk. The frequent, small purchase carries more psychological weight than the infrequent, large one.

The Shopping Frequency Trap

This has a direct consequence for people who shop less often. The authors found that the effect of perceived price changes on inflation expectations is stronger for individuals who shop less frequently (D’Acunto et al., 2019).

Why? Because when you only go to the store once every two weeks, you are exposed to several larger price changes all at once. The cumulative shock of seeing that your usual basket now costs $15 more is more powerful than the gradual drip of weekly increases. A person who shops weekly might absorb a 2 percent increase on eggs one week, then a 1 percent increase on bread the next. A biweekly shopper sees a 3 percent jump on everything at once. That concentrated dose of bad news distorts their view of the whole economy.

This is a subtle but powerful mechanism. It means that your shopping habits, which you think of as a personal preference, are actually part of how you form your economic worldview. And the less you shop, the more distorted that worldview becomes.

What You Don't Know Hurts You

The authors also found that the effect is stronger for people who are more uncertain about inflation in general, and for those who say they do not rely on the media to form their expectations (D’Acunto et al., 2019).

This makes intuitive sense. If you are unsure about where prices are heading, your own personal experience at the store becomes a more powerful anchor. You have less external information to correct it. And if you ignore the news, the price tag on your cereal box is your only source of truth.

Here is the problem. The official inflation measures that central banks use, like core inflation, strip out volatile items like food and energy. They focus on a broad basket of goods that the average consumer buys. But the average consumer does not exist. Your personal basket is different from your neighbor's. And if you are someone who buys a lot of frequently purchased items, your personal inflation rate might be much higher or lower than the official number.

The authors put it bluntly: central banks' focus on core inflation instead of the heterogeneous price changes in households' non-durable bundles might lead to systematic policy mistakes (D’Acunto et al., 2019).

The Human Error in Monetary Policy

Let me explain why this matters beyond the grocery aisle.

The Federal Reserve, the European Central Bank, and other central banks set interest rates based on inflation expectations. They want to keep those expectations anchored around 2 percent. They use sophisticated models and survey data to measure what the public thinks about future inflation. But if those surveys are capturing people's responses to the price of milk, not the official CPI, then the models are built on a flawed foundation.

Consider what happens during a supply shock, like a bird flu that kills chickens and drives up egg prices. The official core inflation measure might barely move. But every household that buys eggs sees a 30 percent price jump. Their inflation expectations spike. They start to expect higher prices everywhere. They might pull back on spending, or demand higher wages. That behavior, driven by egg prices, can then become a self-fulfilling prophecy. Inflation becomes a reality not because of broad economic forces, but because of a psychological reaction to a specific, salient price change.

The authors' work suggests that central bankers need to pay attention to what people actually see, not just what the statistics say. They need to understand that a price shock to a frequently purchased item has an outsized effect on expectations.

What This Study Does Not Prove

This research is not saying that your personal grocery bill is the only factor driving inflation expectations. It is one factor among many, including media reports, government announcements, and your own general economic literacy. The authors controlled for many of these other variables, but you cannot control for everything in a real-world dataset.

The study also focuses on non-durable goods: food, household products, personal care items. It does not cover big ticket items like cars or houses, or services like rent and healthcare. Those are important too, but they operate on a different frequency. A rent increase might be a huge shock, but it happens once a year. The authors found that frequency is the key variable, so the effect of a rent increase on expectations might be weaker than you think.

Finally, the data comes from a specific period (2004-2010) and a specific country (the U.S.). Inflation dynamics vary across time and place. The psychological mechanism is likely universal, but the magnitude of the effect might differ in countries with different shopping habits or media environments.

What This Actually Means

• ▸If you shop infrequently, your inflation expectations are more volatile. Going to the store once every two weeks exposes you to larger, more concentrated price shocks. That can make you feel like inflation is higher than it actually is. Consider shopping weekly, or at least check prices online between trips, to smooth out the psychological impact.

• ▸Central banks should track what people buy, not just what the economy produces. The official inflation basket is designed to measure the cost of living for a representative consumer. But representative consumers do not exist. Policymakers need granular data on what different groups of people actually purchase, and how frequently, to understand how expectations are being formed.

• ▸A price increase on something you buy every week matters more than a price increase on something you buy once a year. This is counterintuitive. You might think the car insurance hike is a bigger deal. But for your brain, the weekly milk price is more salient. If you are trying to manage your own expectations, focus on the big, infrequent costs separately.

• ▸The media can help correct distorted expectations, but only if people pay attention. The authors found that people who ignore the media rely more on their own shopping experience. If you want to avoid being misled by a few high price tags, check official inflation data or read a reputable economic report. It might be boring, but it is more accurate than your receipt.

• ▸This is a warning against using "core inflation" as the sole guide for policy. Core inflation excludes food and energy because they are volatile. But those volatile prices are exactly the ones that households see most often. By ignoring them, central banks risk making decisions based on a reality that does not match the public's experience. That mismatch can lead to policy errors that harm the economy.

Your grocery shopping is not just about feeding your family. It is a daily lesson in economics, and your brain is taking notes. The question is whether the people in charge of the economy are reading them.