Thursday, January 31, 2008

Statistical Discord?

Today's GDP release is boring, so I'm going to talk about something else.

You may be wondering why Canada is reporting data for November two days later than the USA is reporting data for the whole fourth quarter, see story here, for example.

Well, let me clarify. To quote the press release from the Bureau of Economic Analysis in the States:
The Bureau emphasized that the fourth-quarter "advance" estimates are based on source data that are incomplete or subject to further revision by the source agency (see the box on page 3). The fourth-quarter "preliminary" estimates, based on more comprehensive data, will be released on February 28, 2008.

Well, what sort of revisions does the American data get? Well, this information is helpfully provided. From these 'advance' estimates to the preliminary estimates, which correspond to Statcan's release of the December data, the absolute mean revision is 0.5%. Annual revisions and the like over the years add up to an absolute mean revision of 1.2%.

I appreciate the clarity. I can't recall seeing Statscan ever being so forward about the nature of their revisions. While the US data gets a couple of pages about revisions, here's what we get:
With this release of monthly GDP by industry, revisions have been made back to January 2007.

Maybe we should consider learning a thing or two from our neighbours.

1 comment:

Matt Nolan said...

We don't get our GDP data until the end of the following quarter!