In late August, when most polls showed Barack Obama losing his lead over John McCain, Mr Obama's campaign manager, David Plouffe, pooh-poohed the reports. "We don't pay attention to national polls," he said. Today, the question on many Americans' minds is whether they should either.rnThe volatility of polls give good cause to wonder. Each day, a slew of new ones hits the American press, but they very seldom agree. Polls this week, for instance, showed Mr Obama with a lead as great as 14 percentage points or as small as zero.rnOne way that polls can be wrong, some say, is because of the high percentage of young people without landlines. Polling organisations usually call land-lines, because federal regulations targeting telemarketers makes it illegal to dial mobile numbers automatically. But after a recent study by the Pew Research Centre, a non-partisan opinion research group, found that the exclusion of "mo-bile-onlys" (who are mostly young and pro-Obama) could introduce a bias into survey data, many polling organisations now feel pressure to invest the money and time to have humans call more mobile phones.
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机译：8月下旬，当多数民意调查显示巴拉克·奥巴马（Barack Obama）失去了对约翰·麦凯恩（John McCain）的领先优势时，奥巴马的竞选经理戴维·普劳夫（David Plouffe）对此表示震惊。他说：“我们不注意全国民意调查。”今天，许多美国人心中的问题是他们是否也应该这样做。民意调查的波动性令人怀疑。每天，美国媒体上都涌现出许多新媒体，但很少有人同意。例如，本周的民意测验显示，奥巴马的领先优势高达14个百分点，甚至低至零。有人说，民意测验可能是错误的，是因为没有固定电话的年轻人比例很高。轮询组织通常会拨打固定电话，因为针对电话推销员的联邦法规将自动拨打移动电话号码视为非法。但是，由无党派意见研究组织皮尤研究中心（Pew Research Centre）最近进行的一项研究发现，排除“仅运动的单身人士”（主要是年轻人和亲奥巴马）可能会给调查数据带来偏差，许多投票机构现在感到压力，需要投入金钱和时间让人们拨打更多的手机。
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