See, there are multiple weather stations, all reporting temperatures each with its own error estimate at different times.

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These short-term global fluctuations are associated principally with natural oscillations of tropical Pacific sea surface temperatures summarized in the Nino index in the lower part of the figure. 2012 is nominally the 9th warmest year, but it is indistinguishable in rank with several other years, as shown by the error estimate for comparing nearby years.

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Economists today give a margin of error for a GDP estimate.

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Update if I correct for my math error, then the bearish estimate gave a 700 point downside to the Dow.

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This online survey is not based on a probability sample and therefore no estimate of theoretical sampling error can be calculated.

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The estimate also contained an arithmetical error which significantly increased estimated construction rates.

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