Today the ONS issued a statement on inflation containing the sentence: "In the year to October, RPI annual inflation fell by 0.8 per cent, compared with a fall of 1.4 per cent in September".

What is that supposed to mean? That inflation in the retail price index fell by 0.8 percentage points? Or that inflation in the RPI between October 2008 and October 2009 was minus 0.8 per cent? Or neither of the above?
 
In fact, the second guess seems to be right. Year-on-year inflation measured by the RPI was minus 0.8 per cent, October to October. In the period September 2008 to September 2009 it had been minus 1.4 per cent.
 
The headline confirms it. It says “CPI inflation 1.5 per cent, RPI inflation -0.8 per cent". So what the ONS should have said  in the body of the text was “In the year to October, the RPI fell by 0.8 per cent ...”. Maybe that would have been too simple. 
 
No wonder people get confused, says a Straight Statistics reader. It’s good to know it isn’t only me.