The Times, which operates behind a paywall, asked hospital trusts for data on when patients were discharged and other media picked up the result – hundreds of thousands apparently being sent home in the middle of the night. The NHS medial director Sir Bruce Keogh expressed his concern.

But were the figures right? By coincidence the Audit Commission has just been looking at how hospitals ‘code’ the duration of patient stays and found them not wholly reliable.

One NHS information analyst is sceptical, noting a suspiciously wide variation between hospitals. Is this a case of information being put into predefined boxes? Hospitals work with a set of templates, some to do with the time when patients were admitted. Hospital stays are getting shorter but the measuring boxes come from the days when patients were in for several days if not longer.

The first rule in statistics is to ask where numbers come from. You can perform all sorts of manipulations and draw all sorts of conclusions but they are going to be warped if the data you started with is flawed or suspect. A round robin Freedom of Information request elicited lots of data and The Times wrote its story. But it would have been safer to quiz the figures and go back to those who produced them, to check they were recording something real.

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