The U.S. economy has contracted for two straight quarters, intensifying fears that the nation is on the cusp of a recession — if not already in one — barely two years after the pandemic recession officially ended.

Six months of contraction is a long-held informal definition of a recession. Yet nothing is simple in the post-pandemic economy. Its direction has confounded Federal Reserve policymakers and many private economists since growth screeched to a halt in March 2020 as COVID-19 struck and 20 million Americans were suddenly thrown out of work.

One sector of the economy that has remained defiantly buoyant is the jobs market and on Friday, the Labor Department will release monthly employment data that most economists believe will show that hiring, too, has begun to cool.

That would be a sizeable shift in an era that may be remembered for having so many unfilled jobs that there were two available for every American who didn’t have one.

Even as the economy shrank over the first half of this year, employers added 2.7 million jobs — more than in most entire years before the pandemic struck. And the unemployment rate has sunk to 3.6%, near a half-century low. Robust hiring and exceedingly low unemployment aren’t consistent with a recession.

While most economists — and Fed Chair Jerome Powell — have said they don’t think the economy is in recession, many increasingly expect an economic downturn to begin later this year or next.

Either way, with inflation raging at its highest level in four decades, Americans’ purchasing power is eroding. The pain is being felt disproportionately by lower-income and Black and Hispanic households, many of whom are struggling to pay for higher-cost essentials like food, gas and rent. Compounding those pressures, the Fed is jacking up interest rates at the fastest pace since the early 1980s, thereby magnifying borrowing costs for homes and cars and credit card purchases.

Read: Inflation hits record 8.9% in euro area, but economy grows

As a result, regardless of whether a recession has officially begun, Americans have increasingly soured on the economy,

So how, exactly, do we know when an economy is in recession? Here are some answers to such questions:

WHO DECIDES WHEN A RECESSION HAS STARTED?

Recessions are officially declared by the obscure-sounding National Bureau of Economic Research, a group of economists whose Business Cycle Dating Committee defines a recession as “a significant decline in economic activity that is spread across the economy and lasts more than a few months.”

The committee considers trends in hiring as a key measure in determining recessions. It also assesses many other data points, including gauges of income, employment, inflation-adjusted spending, retail sales and factory output. It puts heavy weight on jobs and a gauge of inflation-adjusted income that excludes government support payments such as Social Security.

Yet the NBER typically doesn’t declare a recession until well after one has begun, sometimes for up to a year. Economists consider a half-point rise in the unemployment rate, averaged over several months, as the most historically reliable sign of a downturn.

DO TWO STRAIGHT QUARTERS OF ECONOMIC CONTRACTION EQUAL A RECESSION?

That’s a common rule of thumb, but it isn’t an official definition.

Still, in the past, it has been a useful measure. Michael Strain, an economist at the right-leaning American Enterprise Institute, notes that in each of the past 10 times that the economy shrank for two consecutive quarters, a recession has resulted.

Still, even Strain isn’t sure we’re in recession now. Like many economists, he notes that the underlying drivers of the economy — consumer spending, business investment, home purchases — all grew in the first quarter.

Overall gross domestic product — the broadest measure of the nation’s output — declined at a 1.6% annual rate from January through March because of one-off factors, including a sharp jump in imports and a post-holiday season drop in businesses’ inventories. Many economists expect that when GDP is revised later this year, the first quarter may even turn out to be positive.

“The basic story is that the economy is growing but still slowing, and that slowdown really accelerated in the second quarter,” Strain said.

DON’T A LOT OF PEOPLE THINK A RECESSION IS COMING?

Yes, because many people now feel more financially burdened. With wage gains trailing inflation for most people, higher prices for such essentials as gas, food, and rent have eroded Americans’ spending power,

This week, Walmart reported that higher gas and food costs have forced its shoppers to reduce their purchases of discretionary spending such as new clothing, a clear sign that consumer spending, a key driver of the economy, is weakening. The nation’s largest retailer, Walmart reduced its profit outlook and said it will have to discount more items like furniture and electronics.

Read: India's Mukesh Ambani kickstarts dynastic succession

And the Fed’s rate hikes have caused average mortgage rates to double from a year ago, to 5.5%, causing a sharp fall in home sales and construction.

Higher rates will also likely weigh on businesses’ willingness to invest in new buildings, machinery and other equipment. If companies reduce spending and investment, they’ll also start to slow hiring. Rising caution among companies about spending freely could lead eventually to layoffs. If the economy were to lose jobs and the public were to grow more fearful, consumers would further reduce spending.

The Fed’s rapid rate hikes have raised the likelihood of recession in the next two years to nearly 50%, Goldman Sachs economists have said. And Bank of America economists now forecast a “mild” recession later this year, while Deutsche Bank expects a recession early next year.

WHAT ARE SOME SIGNS OF AN IMPENDING RECESSION?

The clearest signal that a recession is under way, economists say, would be a steady rise in job losses and a surge in unemployment. In the past, an increase in the unemployment rate of three-tenths of a percentage point, on average over the previous three months, has meant that a recession will soon follow.

Many economists monitor the number of people who seek unemployment benefits each week, which indicates whether layoffs are worsening. Weekly applications for jobless aid, averaged over the past four weeks, have risen for eight straight weeks to nearly 250,000, the highest level since last November. While that is a potentially concerning sign, it is still a low level historically.

ANY OTHER SIGNALS TO WATCH FOR?

Many economists also monitor changes in the interest payments, or yields, on different bonds for a recession signal known as an “inverted yield curve.” This occurs when the yield on the 10-year Treasury falls below the yield on a short-term Treasury, such as the 3-month T-bill. That is unusual. Normally, longer-term bonds pay investors a richer yield in exchange for tying up their money for a longer period.

Inverted yield curves generally mean that investors foresee a recession that will compel the Fed to slash rates. Inverted curves often predate recessions. Still, it can take 18 to 24 months for a downturn to arrive after the yield curve inverts.

For the past two weeks, the yield on the two-year Treasury has exceeded the 10-year yield, suggesting that markets expect a recession soon. Many analysts say, though, that comparing the 3-month yield to the 10-year has a better recession-forecasting track record. Those rates are not inverted now.

WILL THE FED KEEP RAISING RATES EVEN AS THE ECONOMY SLOWS?

The economy’s flashing signals — slowing growth with strong hiring — have put the Fed in a tough spot. Chair Jerome Powell is aiming for a “soft landing,” in which the economy weakens enough to slow hiring and wage growth without causing a recession and brings inflation back to the Fed’s 2% target.

But Powell has acknowledged that such an outcome has grown more difficult to achieve. Russia’s invasion of Ukraine and China’s COVID-19 lockdowns have driven up prices for energy food, and many manufactured parts in the U.S.

Powell has also indicated that if necessary, the Fed will keep raising rates even amid a weak economy if that’s what’s needed to tame inflation.

“Is there a risk that we would go too far?” Powell asked last month. “Certainly there’s a risk, but I wouldn’t agree that’s the biggest risk to the economy. The biggest mistake to make…would be to fail to restore price stability.”