The Sunday Telegraph reported this morning that:
“Stroke victims who are admitted to hospital are far more likely to die if they are treated outside central London, an investigation has found. The NHS statistics show survival rates for stroke victims sent to central London hospitals are 54 per cent higher than for those in some parts of the country.”
Fortunately, the ‘Health Correspondent’ Laura Donnelly has got her statistical knickers in a twist. She goes on to write:
“The death rate within 30 days of admission for stroke is 14.6 per cent in the capital’s central sites, according to analysis of the nine years’ data ending 2009 – compared with rates of more than 22 per cent in industrial cities and manufacturing towns”
So, in the poor industrial towns the survival rate is 100% – 22% = 78%. If London is 54% better (154% as good) that makes the survival rate in London 0.78 times 1.54 = 123%. Wow! In London, for every 100 stroke victims taken to hospital, 123 of them survive!
It is the death rate of the industrial towns that is 22% divided by 14.6% = 154%, that is 54% worse. But the vast majority of stroke victims survive, so the survival rate difference is not the same number at all.
Actually, of course the survival rate in London is 100% – 14.6% = 85.4%. The difference in rates is then 85.4% divided by 78% = 109.4%. So London survival is better by a whopping 9.4%.
Not 54%, then.
Never mind, Laura Donnelly, there will be a real scandal along soon if you wish hard enough. Perhaps an introductory high-school statistics text could be put on your Christmas list this year?