"I think that's a very laudable intent, but sometimes that produces a lack of clarity," said former Fed staffer and current partner at Cornerstone Macro Roberto Perli. "Sometimes there is a consensus for one reason and then next time there is a consensus for a different reason so the story shifts and people get confused."
In fact, Fed policymakers' deepening uncertainty about their own projections has resulted in the central bank sending mixed messages — repeatedly ratcheting up rate hike expectations only to tone them down later.
At Wednesday's quarterly news conference Fed officials' doubts were in plain view, with Yellen using the term "uncertain" or its variations 13 times, more than twice as often as in March. In December, when the Fed raised its rates by a quarter point for the first time in nearly a decade, that word only came up twice.
And on Friday, James Bullard, a Fed voter this year, said the economy may need only one rate hike for the next two and half years, and called on the Fed to discard its long-run forecasts altogether, or risk losing credibility with markets.
While most Fed officials still see two rate hikes this year, markets expect only one in December, if at all.
This gap is a source of discomfort for Yellen who places a premium on making sure markets can anticipate how new economic data will guide the Fed's decisions on rates.