Saturday, March 9, 2013

Cooperating with Alfred

I finally figured out where to get the "vintage" data that ALFRED offers. After you find the series you want (in my case, Potential GDP) and after you get a graph on the screen, that's when you click download.

ALFRED then gives you a selection window with several old versions of the data -- all the versions they have, I guess. You just highlight the vintages you want (in my case, all of them) and the thing is ready to send you a file (in my case, a zipped Excel file).

I wanted to look at Potential GDP because, as you know, it has been revised down.

Turns out, the "real" PGDP data from ALFRED comes in not only several vintages, but also several different "base year" series. To whit:

Data ValuesStart Year
Billions of 1982 Dollars1991-01-30
Billions of 1987 Dollars1992-01-22
Billions of Chained 1992 Dollars1997-01-28
Billions of Chained 1996 Dollars2000-01-27
Billions of Chained 2000 Dollars2004-09-13
Billions of Chained 2005 Dollars2010-01-26

If you select one year's data from all the different vintages and make a graph of it, the graph shows an upward-stepping pattern. Upward-stepping, because every time they pick a different base year and adjust for inflation, the number gets bigger. So, if I want to compare vintages across base years, I'll have to adjust for base years. I didn't get into any of that today.

Just for the base-year 2000, ALFRED offers eleven different vintages. The oldest is dated September 13, 2004, and the newest August 27, 2009. That period includes the time of the financial crisis, so I figured I'd look at that.

Graph #1

Move your mouse up and down over the legend to highlight different lines on the graph. You will see that as the mouse moves down toward newer vintages, the highlighted Potential GDP line on the graph is most often lower also.

My Google Drive Spreadsheet is available.

No comments: