How's this for an opener? "More Americans will be shopping this year on Black Friday," divines  Reuters, "or at least that's how it looks from outer space." No, that's not a dispatch from the news wire's Martian correspondent: it's a report on satellite photos being used to gauge the state of the U.S. consumer economy.
Scientists often talk of "proxies": you measure one thing to get an indication of another. In this case, the proxies for shopping activity are cars parked outside shopping malls--visible in satellite photos from Remote Sensing Metrics. Fully 35% of parking spots have been filled since the middle of September this year; that figure was just 31% and 32% in the previous two years. On the Saturday before Black Friday (i.e. four days ago) this year, 42.3% of parking spots were filled, versus just 36.5% in 2009 and 30.6% in 2008.
Translation: the alien's-eye view of the economy looks good this year.
Sometimes, however, clogged parking lots don't necessarily translate into higher retail sales. In 2008, for instance, there were a lot of customers elbowing each other at the shopping malls--but the actual amount of money spent was less than in year prior, since the busted economy had forced retailers to slash prices. But since an analyst tells Reuters that "prices could be higher this year on groceries and luxury goods," the stuffed parking lots could well mean big money this year -- when it comes to luxury goods, that is. The day after Thanksgiving is the one day a year when you are least likely to need groceries.
When scientists use proxies, it's because they don't have access to more immediate forms of measurement. For our part, we'll forego the measurements from outer space, and wait for the direct sales data, coming soon to a mall near you.
[Image: Flickr user marc_smith ]