WASHINGTON, D.C. — The Federal Reserve has spent the last several months telling the country that it is “data-dependent.” That phrase has become, in economic circles, the equivalent of a fortune cookie: technically meaningful, and entirely uninformative until you open it.

This week, the cookie was opened. Fed Governor Christopher Waller said that the inflation report arriving next week will “largely determine” whether he supports a rate hike at the Fed’s upcoming policy meeting — and, in a remarkable display of central-bank suspense, that the odds of a move have settled at roughly fifty-fifty.

A fifty-fifty. The entire direction of the American interest-rate policy, the cost of every mortgage, auto loan, and student loan in the country, is now a coin flip. And the coin, as the Boston Herald noted, does not even flip until next week.

"It may not take much to nudge me toward supporting a rate hike," said the governor in charge of the thing the whole economy is waiting on. He then declined to say what, specifically, 'not much' would be.

The mechanics are simple enough. Waller’s vote, as reported by Bloomberg, hinges on August’s inflation data — the CPI number that will come out in a few days, in a window of time, at a time of day the Fed has not yet confirmed. If inflation is coming down toward the Fed’s two percent target, he may hold. If it is not, he may hike. The market, which has a way of pricing in the unknown, has responded by doing the most honest thing a market can do: it has priced in a coin flip.

THE ONE-NUMBER ECONOMY: AT A GLANCE

  • The number: August CPI, released next week, in a time slot the Fed has not yet publicly confirmed.
  • The threshold: "It may not take much." When asked how much, the answer was that it depends on the number.
  • The stakes: The direction of every interest rate in the country, plus the mood of roughly four million Americans with adjustable mortgages.
  • The precedent: The last time the Fed was this transparently uncertain, the phrase "data-dependent" was still a compliment.

There is a school of thought, mostly in Washington, that the Fed’s transparency is the problem. A central bank that says “we will decide next week based on a number that is not out yet” is, that school argues, a central bank that has made the entire economy a spectator sport. The other school, mostly in the markets, argues that at least the Fed is honest about it, which is more than some institutions can say.

Wall Street, for its part, has done what Wall Street does when the future is a coin flip: it has built an entire industry around the coin. Options on the CPI number are now, by some measures, the most-traded instrument on the exchange. Hedge funds are running models on a number that does not exist yet. Economists are publishing forecasts of a forecast.

At press time, the August CPI was not yet out, the Fed had not confirmed the release time, and Waller had not, when asked a second time, clarified what “not much” actually meant. The number, when it lands, will be either good or bad. The economy, it turns out, has been holding its breath since Tuesday.