CPI against RPI Statistics

The current CPI statistics used gives the UK around 1.2 percent as near as one can remember the quoted figures.

So which is the more accurate for economics forecasting - the current CPI system, or the old RPI figures, and what would the old RPI system be reporting at the moment?


Book Reviewer
Calculating inflation is a can of worms - if you don't smoke you are not affected by tobacco price. CPI and RPI seek to produce a generalised rate based on the price rises of a broad basket of measures. They are both focussed on the "average" household, and the averaging process makes it unlikely that any household actually is average. From time to time the contents of the basket are adjusted to reflect the changing tastes of the UK population.

RPI is "Retail Price Index" and has been calculated since 1947, and still is by the Office of National Statistics. The data should be on their website. As mortgage payments comprise part of RPI and the solution to high inflation is to raise interest rates a second version of the RPI was introduced, which excluded the mortgage part of the calculation. This is known as "RPIX."

CPI is "Consumer Price Index." It was introduced by the Blair/Brown government in 1997 and differs from RPI in having a different basket of goods. Significantly it excludes housing costs. CPI is regarded with some suspicion as it is (allegedly) easier to manipulate.

Wikipedia is a good place to start if you week further enlightenment. ONS has data for all on its website (somewhere).
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