# from a year earlier

Usage example with a context:

The weakened ruble has dramatically impacted the rate of inflation, which accelerated in February to hit 16.7 percent from a year earlier.

Is this a set phrase or something of that nature? I suppose it should be understood as from the previous year, that is, the year that directly followed the current year. Is my understanding correct?

• The set phrases that mean (price level in February 2015) divided by (price level in February 2014) are "year over year" and "in the twelve months ended February 2015". The latter is often abbreviated to "the February 12ME". – Jasper Mar 10 '15 at 17:13
• "Annual rate" is another set phrase, but it is ambiguous in multiple ways. The problem is that you can use any time period, and then extrapolate (or interpolate) in various different ways. For example, you could calculate the inflation rate in February, and multiply by 12. Or you could calculate the inflation rate in February, and multiply by 365 (days per year) / 28 (days in February). Or you could compound the inflation -- (1 + monthly inflation)^12 - 1. Or you could do a similar calculation using a quarter's inflation, or five years' inflation, et cetera. – Jasper Mar 10 '15 at 17:17
• When describing interest rates, "annual percentage rate" is an annual rate that is calculated without considering the effect of compounding. "Compound annual rate" is an annual rate that does take into account compounding. – Jasper Mar 10 '15 at 17:19