This is the latest entry in NPP’s weekly Data Wednesday series, intended to introduce new users to our Federal Priorities Database.  All posts are archived here.

In last week’s Data Wednesday post, we showed you how to time travel on the Federal Priorities Database map. This week, we’ll discuss something important to keep in mind when comparing numbers between years: inflation.

Inflation is the change in purchasing power over time. For example, a dollar in 1993 bought more than a dollar would buy today. So when looking at a money-related dataset, you can’t compare a 1993 dollar amount to a 2011 dollar amount—they don’t represent the same thing.

The Federal Priorities Database can adjust for inflation, transforming all historical dollar amounts to their value in today’s dollars:

1. Run a database search, keeping in mind that only money-related datasets can be adjusted for inflation (it wouldn’t make sense to adjust unemployment rates, for example).
2. Once you see the search results appear on the map, look for a checkbox labeled Show in FY 2012 dollars (directly below the map legend).
3. Click the checkbox, and the database will adjust all dollar amounts to their fiscal year 2012 values (currently it is fiscal 2012; the federal fiscal year began on October 1st and runs through September 30th, 2012).

Now that all the numbers are expressed in current dollars, you can compare them over time.