Tuesday, September 26, 2017

"City Travel Scaling"

We've followed and enjoyed the author of the piece below, George Mason University econ/polymath Robin Hanson for years so I hope what I'm about to say isn't misconstrued by anyone.
When he writes "The book Scale is on an important yet neglected topic" he displays a small conceit.
More below.

From Overcoming Bias:

Here’s a fascinating factoid I found in Geoffrey West’s new book Scale:
An extremely simple but very powerful mathematical result for the movement of people in cities. .. Consider any location in a city. .. predicts how many people visit this location from any distance away and how often they do it. .. It states that the number of visitors should scale inversely as the square of both the distance traveled and the frequency of violation. ..

Suppose that on average 1600 people visit there area around Park Street, Boston from four kilometers away once a month. .. only 400 people visit Park street from 8 kilometers away once a month. .. how many people visit Park street from four kilometers away but now with a greater frequency of twice a month. .. also … 400 people. (pp.347-9)
As cities are basically two-dimensional in space and one-dimensional in time, this implies that most visits to a place are by people who live nearby (not so surprising), and also by people who visit very infrequently (quite surprising). I’d love to see an urban econ model embodying this pattern. Alas West cites “Markus Schlapfer and Michael Szell”, but no publication, nor could I find one online.

The book Scale is on an important yet neglected topic: basic patterns in large systems such as organisms, ecosystems, cities, and firms. Alas West rambles, in part to avoid talking math directly, so you have to skim past many words to get to the key patterns; I bet I could have described them all in ten pages. But they are indeed important patterns....MORE
Professeur Hanson, permettez moi de vous présenter Mme Izabella Kaminska, a fellow polymath:

August 2015
The Problem With Silicon Valley Is The Scale
July 2016
Izabella Kaminska Talks Scale

Also in 2016, Irving Wladawsky-Berger who, if the Order of polymathy had classes would be a Knight Grand Cross of the Most Excellent Order of the Polymath had "Scale: 'Why People and Companies Die While Cities Keep Growing'" but Izabella came right back in June 2017's:
Today On Book Nook, the FT's Izabella Kaminska Reviews "Scale" (Why Cities Keep Growing, Corporations And People Always Die, And Life Gets Faster*)
Oh and she interviews the physicist/complexity-scientist author as well....
Which I ended, as I often do, with some links to previous related (and unrelated) posts: 

.... "The Philosophy of Complexity: Are Complex Systems Inherently Tyrannical?"
In the end the universe itself is inherently tyrannical.
You are not the boss....
Sic semper tyrannosaur
Or something.
As the philosopher Sting said to Tyrannosaurus' cousin (who is actually Apatosaurus but syllable count):
Hey there mighty brontosaurus
Don't you have a message for us
You thought your rule would always last
There were no lessons in your past
We have quite a few other complexity posts but most, sadly, are sans dinosaurs.

Like Izabella and the good Professor we recognize there are limits to the analogy. See for example:

Size Matters: The Source of the Small-Cap Premium
This type of argument is usually more facile than deep and the attempt to transfer a paradigm constructed by observing natural phenomena to business or finance usually results in the Rock Man Syndrome.*
Still, there might be something in here to make a buck off of.
From Above the Market...