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11-08-2008, 07:07 AM
 Location: from houstoner to bostoner to new yorker to new jerseyite ;) 4,085 posts, read 11,457,484 times Reputation: 1942

I was a-googlin' and ran into this Austin Contrarian: Density calculations for U.S. urbanized areas, weighted by census tract and found it interesting. It ranks cities by weighted density using 2000 census tract numbers. (An explanation of "perceived" and "weighted" density here. Austin Contrarian: Perceived density) By this metric, Houston is almost as dense as Portland, and denser than Pittsburgh. Is this a good way to compare densities between cities? What do you think?

11-08-2008, 10:40 AM
 Location: DFW Texas 3,096 posts, read 6,778,839 times Reputation: 2141
Quote:
 Originally Posted by houstoner I was a-googlin' and ran into this Austin Contrarian: Density calculations for U.S. urbanized areas, weighted by census tract and found it interesting. It ranks cities by weighted density using 2000 census tract numbers. (An explanation of "perceived" and "weighted" density here. Austin Contrarian: Perceived density) By this metric, Houston is almost as dense as Portland, and denser than Pittsburgh. Is this a good way to compare densities between cities? What do you think?

I thought density was total population divided by land area? If what that table states is true LA is denser than NYC?? Nah!!

11-08-2008, 12:09 PM
 Location: yeah 5,716 posts, read 14,578,414 times Reputation: 2829
Quote:
 Originally Posted by JVTX72 I thought density was total population divided by land area? If what that table states is true LA is denser than NYC?? Nah!!
metro areas.......

11-08-2008, 04:00 PM
 Location: Chandler, AZ 134 posts, read 113,102 times Reputation: 63
Uhm, please, Phoenix denser than Portland? Not a chance...

11-09-2008, 11:23 AM
 Location: Tijuana Exurbs 4,002 posts, read 10,454,004 times Reputation: 4730
There are some VERY odd things going on with the numbers included in this matrix that need some explaining for readers to make sense of it. For example,#2 (SF)and #6 (SJ), even when combined only have 4.5 million people. That means about 2.5-3.0 million people are missing from the standard definition of the San Francisco Bay metro area. The same holds true of Riverside-San Bernardino which is missing about 1.5-2.0 million people. I suppose I could read the links provided for an explanation, and I probably will, but I think the OP should have at least given us a summary explanation.

11-09-2008, 11:30 AM
 2 posts, read 2,662 times Reputation: 12
This is my work.

The figures are for "urbanized areas," which is the Census Bureau's term for the built-up, contiguous urban area. ("Urban" means a density of >1,000 ppsm). Using urbanized area eliminates the arbitrariness of city or metropolitan area boundaries.

The idea behind weighted density is this: Most people in a city may live at a very high density, but standard density (total population divided by total land area) does not capture this. For example, suppose we have a city of 10,000; 9,000 of these live in 1 sq. mile, while the other 1,000 are spread out over the other 9 square miles. The standard density is 1,000 ppsm, which ignores that most people live much more densely than this.

Weighted density fixes this. We calculate the standard density of each square mile. But when calculating total density, we assign each square mile a weight equal to its share of the total population. In this example, the dense square mile would get a weight of .9 since it has 9/10s of the total population. The other square miles would get, collectively, a weight of .1. Then the weighted density is .9(9,000 ppsm) + .1(111 ppsm) = 8,111.1 ppsm. This accurately reflects the fact that most people live densely.

I use census tracts as the base geographic unit, because they roughly correspond to extended neighborhoods.

JVTX72, you have misread the chart. LA's <i>standard density</i> is higher than NYC's. Using weighted density, NYC is much denser, reflecting that many New Yorkers live at very high densities (>100,000 ppsm). Weighted density, in other words, cures the tendency of standard density to understate some cities' density.

Walkingthecow, it is a fact that Phoenix's urbanized area is denser than Portland's under either metric. Most people have a gut reaction like yours, but that's why we go to the data; gut reactions are often wrong.

There is much more here: [url=http://www.austincontrarian.com/austincontrarian/density/]Austin Contrarian: Density[/url] (including a regression of transit use on weighted density)

11-09-2008, 11:31 AM
 2 posts, read 2,662 times Reputation: 12
kettlepot, these are 2000 census figures and 2000 census definitions of urbanized areas. The explanation is that, in 2000 at least, SF's and SJ's urbanized areas were not contiguous; if they had been contiguous, the census bureau would have counted them as a single urbanized area.

Last edited by AustinContrarian; 11-09-2008 at 11:33 AM.. Reason: grammar
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