Stanley Fischer, vice chairman of the Fed said this afternoon he believed the US would soon meet the Fed's targets for full employment and inflation of two per cent, implying he believes the time for the second rate rise since the recession is approaching.
Meanwhile, Yellen is expected to address not only the timing of the next interest rate rise but also innovative ideas about whether the Fed should ditch its dual mandate of targeting inflation and employment when she speaks at the symposium on Friday.
Markets have put the chances of an interest rate rise at some point this year at just over 50 per cent, but Yellen and her Fed colleagues have been keen to stress they believe markets are underestimating the central banks' willingness to act. This has led to criticism that the bank "has confused markets", according to Bank of America Merrill Lynch's Michelle Meyer.
In this light, analysts do not think Yellen will give any concrete clues about the timing of the next rise. Instead, she is likely to indicate more broadly that the second rate rise since the recession is firmly on the Fed's agenda.
"We don't expect her to provide any strong steer on the timing of the next rate hike," said Capital Economics. Joshua Mahony of IG added any comments about specific dates for action might be pointless given the Fed's recent propensity to delay: "There is little space for manoeuvre, with any hawkish comment from Yellen likely to be seen through cynical eyes given the perception of can-kicking in 2016."
BAML's Meyer agreed, adding: "Yellen might argue that conditions are increasingly being met to further normalise rates before the end of the year ... However, we do not expect guidance on the exact timing of the next hike."
Away from the perennial rate-guessing game, the Jackson Hole meeting has a reputation for more experimental thinking, and Yellen is also set to discuss what she thinks of ideas for a more fundamental shake-up at the Fed.
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Michala Marcussen, chief economist at Societe Generale said she is "keen to see if the chair addresses recent suggestions, both from Fed officials and academics, on raising the Fed's inflation target or targeting a variable such as nominal GDP."
In a paper last week, chair of the San Francisco Fed, John Williams argued the years since the recession had reduced the real interest rate to such an extent that raising the inflation target from two to four per cent would give the central bank more flexibility to slash rates in the event of a future slowdown.
If Yellen signals her interest in such a policy it will be difficult to predict the market reaction, given how primed they are to viewing every utterance from the central bank through the prism of what it means for interest rates. However, as Chris Hare, a former Bank of England economist now at Investec, noted: "Much more importantly for the bigger picture ... is an increasing view among central bankers, and investors, that we might have entered a structurally weaker, low growth, low interest rate world."