Nishimura also said the market's view on the timing of a policy change won't necessarily match the BOJ's before the central bank alters its policy. He suggested that the BOJ may raise interest rates even before market players fully discount a policy change into rates. "The central bank will not manipulate markets on economic and policy views," he said, adding that "regarding policy change, we need to carefully watch and examine all economic data in order to grasp or check the outlook for the economy," Nishimura said. He added that consumer prices alone will not determine the BOJ's monetary policy. "Prices are less sensitive to economic activities and are having difficulty rising," Nishimura said. Japan's nationwide core consumer price index rose 0.1% in October from a year earlier. It was the fifth straight month of increases but slightly missed a consensus forecast of economists for a 0.2% gain. The index lifted 0.2% in September and 0.3% in August. "(The core) CPI remains weak but I think the index will likely stay within our forecast," he said. Uncertainty over economic data is increasing, but this uncertainty will not impede a change in policy, he said. He added that the yen-carry trade is one such uncertainty, though he didn't elaborate. "When we pass judgment on policy on the basis of available economic data, uncertainty over the economy and data always continues. But we need to judge policy, if necessary, amid uncertainty," Nishimura said. Yen carry trades involve borrowing yen at low interest rates and then investing the money in higher-yielding foreign assets. The BOJ's next policy decision meeting is scheduled for Dec. 18-19, on the heels of the release of the BOJ's December tankan corporate sentiment survey due Dec. 15. Some market players are still speculating that the central bank may raise interest rates at the meeting.