Thursday, September 24, 2009

How does Sharjah's economy look from space?

Consider the abstract from Measuring Economic Growth from Outer Space, J. Vernon Henderson, Adam Storeygard, David N. Weil, NBER Working Paper No. 15199, Issued in July 2009:
GDP growth is often measured poorly for countries and rarely measured at all for cities. We propose a readily available proxy: satellite data on lights at night. Our statistical framework uses light growth to supplement existing income growth measures. The framework is applied to countries with the lowest quality income data, resulting in estimates of growth that differ substantially from established estimates. We then consider a longstanding debate: do increases in local agricultural productivity increase city incomes? For African cities, we find that exogenous gricultural productivity shocks (high rainfall years) have substantial effects on local urban economic activity.
All kidding aside, you could apply this framework to oil prices and economic activity in oil-rich states.

Here's an un-gated version of the paper.

More in this September 21st article in Seed Magazine:
Henderson cites the Democratic Republic of Congo as an example of where data quality is poor. According to the Penn World Table, a standard source used to measure economic growth across countries, during the period from 1992 to 2003 the country had negative GDP growth. In that same period, the satellite data shows a marked increase in nighttime light intensity, suggestive of positive growth, likely in the informal sector. Henderson says Myanmar’s numbers, on the other hand, may show political manipulation: Nocturnal lights indicate significantly lower GDP growth than that stated by the ruling military junta.

Henderson and his colleagues also used the DMSP data to examine economic activity on sub-national scales, investigating the relationship of African cities to nearby agricultural regions. They found that years of crop-boosting high rainfall in a city’s hinterlands significantly correlated with increased growth and development in the urban center as measured by artificial lighting intensity.
A NOAA team led by Chris Elvidge removes contaminating natural phenomena from the images like moonlight, cloud cover, lightning, polar auroras, and forest fires, but human choices of how buildings and streets are lit, the ways windows are shuttered, and even which variety of light bulbs are used all alter the patterns and intensity of light, adding uncertainty to any conclusions.
Of course once this becomes widely known, the Myanmars of the world may ban shutters and change the kind of outdoor lighting they use. D'oh!


Blogger BuJ said...

Very smart! I liked this post.

I indirectly compare lights when doing night time plane landings and flights at high altitude over cities.

I noticed for example that Birmingham UK is a city many times the size of Dubai and yet even with the best visibility, the lights of Dubai always seem a bit too much during landing compared to Birmingham!

Surely B-ham is higher than Dubai in urban density, GDP/capita, and GDP/sq km, as well as the usual footprint km and total population.

Also worth noting on a typical flight from say Dubai to London that cities get typically brigher as u go west.

Iran> Iraq > Turkey = dim lights

Bulgaria > Romania > = slightly brighter

Germany > the Netherlands = brighter still


Thumb's up!

11:50 PM  
Blogger Tim Worstall said...

Thought this might amuse John:

A different view of the same paper.

2:26 PM  

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