WASHINGTON >> Seven years ago, when Republicans passed the most significant overhaul of the tax code in a generation, they were sure the law would supercharge investment, raise wages and shift the U.S. economy into a higher gear.

So did it?

The answer, at least for now, is largely lost to history.

A pandemic and a surge in inflation convulsed the global economy not long after the law passed in 2017, scrambling the data that analysts would have typically relied on to draw conclusions about whether the tax cuts helped the economy grow the way Republicans had promised.

As a result, policymakers in Washington are now relying on only a partial understanding of the law’s past as they weigh committing roughly $5 trillion toward continuing it.

“Basically, from 2020, the data is kind of useless,” said Alan Auerbach, an economics professor at the University of California, Berkeley, who counts Kevin Hassett, a top economic adviser to President-elect Donald Trump, among his former students.

Economists have focused on just two years before the coronavirus pandemic, 2018 and 2019, to measure the law’s consequences for the most important economy in the world. But that’s a limited window for trying to discern whether the tax cuts prompted a cycle of investment and growth that can take years to play out.

“In terms of looking at longer-run effects, pretty much just forget about it,” Auerbach said. “There’s just no way to control for the effects of COVID.”

Not that everything about the 2017 tax law is a mystery. The legislation slashed marginal tax rates for almost every individual income bracket, created a larger standard deduction and expanded the child tax credit. For businesses, the law cut the corporate rate to 21% from 35%, temporarily incentivized new capital investments, overhauled the taxation of earnings overseas and offered a new deduction to owners of many typically smaller companies.

To Republicans, who passed the law over unified Democratic opposition in the first year of Trump’s first term, these changes amounted to an unqualified economic success. They credit the tax cuts with strong growth and wage increases in the years before the pandemic, warning that letting many of the 2017 cuts expire, currently scheduled to happen at the end of the year, would create an economic drag.

“We saw the power of these tax cuts in ‘18, ‘19 and going into January of ‘20 before they were interrupted by COVID, and the great success that we had,” Scott Bessent, Trump’s pick to lead the Treasury Department, said at his Senate confirmation hearing Thursday. “If we do not renew and extend, then we will be facing an economic calamity.”

Economists are more circumspect. Trying to pinpoint the role that any single factor plays in a sprawling economy shaped by changing interest rates, oil prices and dozens of other variables is an inherently difficult task. Only with carefully constructed models do economists offer some findings about how a tax cut affects the economy.

They generally view tax cuts for individuals as having little effect on the economy overall, despite their popularity. Economic research suggests that marginally lower tax rates do not motivate people to work more, which could bolster growth, and the money that Americans save from lower taxes does not affect the economy in a lasting way, either. So some of the most expensive pieces of the 2017 law — the lower individual rates and larger standard deduction — are most likely the least important to the economy.

That leaves much of the scholarly focus on the corporate tax cuts included in the 2017 law. Textbook economic theory states that lower taxes cause companies to invest more in their businesses, which in turn helps make workers more productive, lifting wages and the prospects of the entire economy.

In a paper last year, a team of researchers from Harvard, Princeton and the University of Chicago reviewed several different ways of measuring the corporate response to the tax cuts. Despite some of the scattered data, the academics concluded that the lower corporate tax cuts had in fact helped stimulate more corporate investment.

The team then used what Eric Zwick, an economist at the University of Chicago and one of the paper’s authors, called “back of the envelope” modeling to extrapolate the effect of higher corporate investment to the performance of the entire economy. They estimated that the law would help the economy become 1% larger over 10 years, growth that in turn pointed toward roughly $750 more in wages for each American worker. Such an increase would still be far below the $4,000 per employee that Trump’s White House had originally promised the corporate tax cuts would generate.

The research from Zwick and his colleagues threw cold water on the Republicans’ insistence that the tax cuts paid for themselves. Even with the added growth that Zwick and his co-authors found, they maintained that the lower corporate taxes had cost the U.S. government billions.

Estimates at the time of the 2017 law’s passage found that it would add $1.5 trillion to the deficit over 10 years.