In my neck of the woods, the Retail Price Index or RPI is a measure of inflation. It is a measure that’s calculated monthly and it represents the cost of a sample size of goods. Unlike the Consumer Price Index, the RPI measures the prices of different sets of goods, giving rise to a change in price.
For example…
The Retail Price Index for the first eight months of 2016 shows that it has continued the increasing trend, growing from 258.8 in January 2016 to 264.9 in October 2016.