A trader wears a hat displaying President Trump’s name while working on the floor of the New York Stock Exchange in New York on Jan. 20. (Michael Nagle/Bloomberg)

March 21: The Dow closed down nearly 240 points on Tuesday, the largest single-day decrease since Donald Trump won the 2016 election. In light of that, we’re republishing this article from February about the administration’s previous comments on using the Dow as a barometer. New comments from press secretary Sean Spicer have been added.

To hear President Trump tell it, the most successful day he’s had since winning the presidency was Dec. 7.

What happened on Dec. 7? Well, Trump got into a fight with a union leader on Twitter. He’d introduced his pick to run the Defense Department at a rally the night before. His declaration the previous day that an investment group would pour billions into creating new jobs in the United States was turning out to be more complex than that, but it was still in the news.

So, why was this Trump’s best day? Because the Dow Jones industrial average went up 1.55 percent over the previous day’s close. And as Trump and his adviser Kellyanne Conway made clear on Twitter over the past 24 hours, the performance of the Dow is a direct indicator of how well the president is doing.

Granted, this wasn’t always the case. As Sopan Deb of the New York Times pointed out Thursday morning, Trump had a different perspective on the growth in the Dow when Barack Obama was president.

Speaking to reporters on his campaign plane Sept. 5, Trump called the stock market “artificial.” “It’s free money,” he said, “because the rates are so low. It’s an artificial market. It’s a bubble.” At that point, the market had improved 8 percent since the beginning of the year. The market is now up 12 percent since Election Day, even though rates ticked up. Yet for some reason, Trump no longer thinks that the market is artificial.

(With that mention of the Times, it’s worth noting something else. If stock market increases are a sign of success, Trump should perhaps stop referring to the Times as “failing” on Twitter.)

If Dec. 7 was his best day, by Trump’s new metric, Jan. 30 was his worst.

That day — and the following, when the Dow also slipped — the country was roiled by his executive order banning refugees from all countries and immigrants from a number of primarily Muslim countries. Some analysts actually did credit the decline to Trump’s policies and Cabinet-nomination troubles. The increase on Dec. 7, for what it’s worth, was credited to the strong economy, with Reuters noting that “the gains came even as Trump’s comments on prescription drug pricing wounded the healthcare sector.”

There is an obvious risk for Trump and Conway to link their job performance to the Dow. The Dow moves based on a lot of things, most of which are out of the president’s control. It also has a habit of suddenly and dramatically moving downward, which will prompt a lot of critics of the administration to point to those tweets above.

But if Trump and his team think the Dow is a good indicator of how he’s doing, so be it. That gives us the opportunity to see how Trump is doing in near real-time — at least while the markets are open. Every five minutes, we’ll check the status of the Dow over the course of the day and use it to power the tool below. If the Dow is up, Trump’s doing a good job. If it’s down, he’s failing.

This isn’t our standard, mind you. It’s Trump’s. At least until such time as it becomes inconvenient for him to point to the Dow as proof of how good a job he’s doing.

Update: On Tuesday, Sean Spicer dismissed the idea that the Dow’s dip on March 21 indicated that Trump’s job performance was suffering.

“Well, I think to look at any one day is — is nothing that we’ve ever — we’ve always cautioned,” Spicer said. That “we” apparently excludes Kellyanne Conway.