Extra tests are inexpensive compared to the cost of error, including the cost of incarcerating the wrongfully convicted.

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Sometimes an error can be a misprint, such as an extra zero that makes the bill jump from three figures to four.

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What started out as a simple error was compounded when the recipients decided to take the extra step and turn it into credit fraud.

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In 2009, HMRC set itself a target of halving the rate of tax credit fraud and error from 9% to 5% by March 2011 and diverted around 400 extra staff to help with the effort.

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He was supposed to spend an extra four years in prison for punching a prison officer in the face in 2006, but a clerical error led that sentence to be recorded as one to be served simultaneously with his previous sentences.

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