PRODUCTION NOTES

Anon

Hi, thanks for your comments. (mark@dslreports.com here)

Yes there is more red than green on the map, but - as someone points out below - it's difficult to tell how many green CO's there are when they all merge.

And anyway, the % of people served by a DSL Co is a more interesting number than % of COs itself.

Here, belatedly are some productions notes:

How The Map Was Generated

The Facts

The ingredient data came from three sources:

1. Polygon data for all of the 50 states from the US Govt (Sorry AK and HI - we will work on fitting you into future maps).

2 A database of COs and their longitude and latitude (Well actually their 'v and h' from an telco grid system- we converted those to long, and lat.)

3. Our database of DSL availability at each CO. This is changing all the time, so watch out for revisions. This is obtained from the CLECs and (most) ILECs - not ISPs.

We used a simple 'sinusoidal' map projection to plot the statelines and then for every CO we know about we project it on to a red pixel for a non- DSL one and a green for a DSL enabled one.

Points to Note

Where real COs are tightly packed - in urban areas - you could have several CO's all being mapped to the same pixel on that map image.

This means that if you look at those big green blobs over the cities they are actually understating the number of COs in that locality: One green CO in Hicksville (Long Island, NY) looks the same on this map as the 20 COs fifty miles to the west on Manhattan.

Oh, and if a red and a green dot are going for the same position, we let the green dot win.

And, er, because DSLAMS do get decommissioned we might - as someone has rightly pointed out - need a third color for COs which were enabled but sadly are no longer so.

The COs are where the people are

We could point you to some cool maps on the US Census site showing all manner of population densities dynamically plotted for you on a map of the US but it would probably overload their web-server.

But take it from me, the pattern of COs (red and green combined) looks very like a population density map of the US.

And here's an interesting feature: Take a look at a Rand McNally map of Kansas and compare it with our CO map: All those (unfortunately red) dots lining up in a matrix is not an artifact of our mapping algorithms. No, the highway system in KS looks like a blow-up of midtown Manhattan but with 50 mile wide blocks and a town with its own CO at on every corner. (There's a night-time shot of the world from space somewhere on the web, and you can see the lights of those same interections).

Why are the green COs where they are?

Well, the areas where the dots are close together (in cities) will have a disproportionately larger number of people living close to a CO.

There are also other factors such as the skew of disposable income to the suburbs, businesses to the city centers, etc. etc.

Two good reasons to help you decide where to invest your money if you're installing DSLAMs.

We'd like to test these hypotheses with some quantitative studies. Watch this space.

There does seem to be a lot of densely packed red dots in the mid-west though .... Maybe we're missing something?

Which brings us on to ...

Future Data Acquisition

Anyway, we will be working on making it easier for us to process new information sent to us from those of you on the ground who can tell us what the local telco is up to better than the telcos do.

Thanks for all of your comments.

[text was edited by author 2001-02-26 22:03:06]

permalink · 2001-02-26 21:55:39 · Print ·

PRODUCTION NOTES

grossly inaccurate map

Re: PRODUCTION NOTES


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