THE outcome was never in doubt. On December 12th America's central bank kept short term interest rates unchanged at 5.25%. What mattered was the statement accompanying the Federal Reserve's decision. Although Ben Bernanke and his colleagues gave a nod to the slowing economy (noting that the cooling of the housing market had been "substantial" and that recent economic indicators had been "mixed"), they repeated that they still considered inflation a bigger worry than weak growth.
　　That is not what Wall Street has been thinking. According to the latest Blue Chip monthly survey, four out of five financial forecasters reckon the central bank's next move will be to cut the federal funds rate. Some onceoptimistic seers have been busy cutting their growth forecasts. The price of fedfunds futures suggests that financial markets see a 20% chance of lower interest rates by April. This had been close to 70%, but unexpectedly strong growth in jobs and then retail sales in November has caused some in the markets to think a rate cut less likely.
　　The central bankers are simultaneously more cautious and more optimistic than many on Wall Street. With core inflation still well above the 1-2% rate they unofficially deem appropriate, Mr. Bernanke and his colleagues are genuinely worried about price pressure. Although fuel costs have fallen sharply, core consumer prices, which exclude the volatile categories of food and energy, still rose by 2.8% in the year to October. (November's figures will be released on December 15th.) The Fed's preferred price gauge, the core personalconsumption deflator, went up by 2.4% in the year to October, only a little short of the fastest pace for a decade. With inflation still too high, cautious central bankers see scant reason for abandoning their hawkish rhetoric.
　　By the same token, the officials are less concerned by the risk of a slowdown than their counterparts on Wall Street are. Not only do the central bankers expect the economy to grow below its trend rate in the short term; they want it to. That is because a period of belowtrend growth will help dampen inflationary pressure by increasing the amount of slack in the economy. Fed officials worry that labour markets, in particular, are too tight. In their July forecast the central bankers expected an average unemployment rate of between 4.75% and 5% for the fourth quarter of 2006 and 2007, well above today's 4.5%. Modestly higher joblessness would be welcome. That unemployment has not risen suggests the economy has not slowed much below its trend rate of growth.
　　 If prudence is telling the central bankers to stand pat, so is their optimism. The Fed is not among those who believe that America's unexpectedly deep housing bust will drag the rest of the economy down. In a recent speech Mr Bernanke made it clear that he saw little sign of the housing recession spreading elsewhere. A stream of weak statistics in subsequent days, particularly a report hinting that manufacturing was in recession, suggested that his optimism might be misplaced.

　　12月12日美国央行决定保持短期利率（5.25%）不变，这个结果早在意料之中。与此同时美联储发表的声明显得更为重要。虽然本•伯南克及其同仁（注意到房地产市场显著降温，近期的经济指标喜忧参半）已承认经济滑坡，他们重申，通货膨胀比疲软的经济更令人担忧。
　　华尔街所见不同。根据最新的每月蓝筹股调查表明，五位金融预报员中就有四位认为央行的下一步举措将降低联邦基金利率。一些一度十分乐观的观察者们现在忙于降低他们对经济增长的预期。联邦基金期货的价格显示，金融市场认为四月前降息的可能性为20%。这一可能性曾经一度接近70%，但就业率以及之后11月的零售额出人意料地上升，引起了一些市场分析人士认为降低利率已不太可能。
　　与许多华尔街人士相比，美联储更加谨小慎微，同时也更加乐观。核心通胀率仍比他们的非官方默认值（1-2%）高出好些，伯南克及其同仁着实为价格压力捏了一把汗。虽然燃料价格大幅下降，核心消费品价格（不包括波动较大的食品和能源类）到今年10月份仍上升了2.8%。（十一月的数据将于12月15日发布。） 美联储偏爱的价格量尺，核心个人消费支出平减指数，到今年10月份上升了2.4%，与十年来的峰值只差一步之遥。通胀率持续过高，谨慎的美联储更没有什么理由放弃他们的鹰派作风。
　　同样，政府官员对可能出现的经济滑坡，没有华尔街人士那么忧心忡忡。美联储不仅预测到经济增长会在短期内低于趋势水平，他们的希望也正是如此。这是因为一段时期的低于趋势水平的增长将使经济更加松弛，从而有助于缓解通货膨胀的压力。美联储官员尤其担心劳动力市场过于紧张。央行7月预计2006年最后一个季度及2007年的平均失业率在4.75%到5%之间，明显高于现在的4.5%。适当高的失业率是有好处的。失业率没有上升显示，经济增长速度比趋势水平低，但差距不是太大。
　　如果出于对通货膨胀的警惕,联储蓄要做出强硬的态度，那么他们的乐观大概也是这个原因。有人认为美国房地产行业的意外破产会拖累整个经济体，美联储并非其中之一。伯南克在最近的一次讲话中明确指出，他未见房地产市场萧条有任何扩散到其他行业的迹象。之后数日，一连串不尽如人意的数据，尤其一份暗示制造业陷入低迷的报告，都说明他的乐观情绪放错了地方。