When the margin of error is taken into account, Labour could actually be behind the Conservatives.

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Cities close together in the standings may have very different prices, while others further apart can be effectively level with each other, taking into account margins of error for price and expenditure data, which the firms don't share with the public.

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Having established the reality of his point, he then designed a mathematical model that tried to take into account and quantify sources of error.

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Also, take into account the possibility of human error.

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Any real-time account of what happened that night is likely to be fraught with mis-remembering and error.

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