Written a paper on how we can compare and even integrate space syntax with spatial interaction. You can get it here by clicking on this link or on the image above. This is based on the notion that we need to develop a way of disentangling the underlying planar graph of the street network into components that when put together either lead to operations on the planar graph itself as in spatial interaction or on the dual of this graph between the streets which is the graph used in space syntax. The link is obvious when developed in this way but the ways of integration are somewhat convoluted. We develop these ideas for some simple hypothetical graphs and make comparisons of the various accessibilities associated with these graphs which appear both in space syntax and spatial interaction. We then develop a semi-real application using data on the nearest neighbour generic graph for Greater London and this reveals the problems of specifying this graph in the first place. Our comparisons with real data are disappointing for many obvious reasons but what I think this paper does is throw light on space syntax and on ideas about accessibility, suggesting that we need a sustained effort to develop the right sorts of underlying graphs from which space syntax can be developed. We are only at the beginning of the process and in space syntax, we have not really explored the properties of the underlying graphs in any depth hitherto. This establishes directions for further research. Click here for the paper.
Joana Barros and Mike Batty write about their work on the BBC Brasil Web Site. Read their article here which is about how transport segregates people rather than linking them together in cities in Latin America such as Sao Paulo. This is from their ESRC Resolution Project with Chen Zhong and Duncan Smith where they are comparing Sao Paulo with London and working with the group at the University of Sao Paulo and INPE.
You may think that this blog has enough on ‘models’ to sink a ship and I have a new editorial on this in EPB. But there is a wonderful article by Paul Krugman on models which I have just come across although written two decades or so ago. Krugman compares evolutionary theory with evolutionary economics in a talk given to the European Association for Evolutionary Political Economy in 1995. The talk is republished here and although it says much on evolution and economics, he has some choice comments about how we should deal with models of the economy (and cities I hesitate to advance). In essence, he says that simulation models must always be interpreted from some meta model, some toy model that abstracts to the point where one really has two models: the full blown simulation and the handy reference – the toy model. He says: “By all means let us use simulation to push out the boundaries of our understanding; but just running a lot of simulations and seeing what happens is a frustrating and finally unproductive exercise unless you can somehow create a “model of the model” that lets you understand what is going on”.
In short he argues that we need models as metaphors and he concludes that: “In short, I believe that economics would be a more productive field if we learned something important from evolutionists: that models are metaphors, and that we should use them, not the other way around”. As all our theories are abstractions, then models represent the way we make these abstractions more practical, more operational. I have had another go at reclassifying models in our urban realm largely because they are continually morphing into new forms and the emphasis is changing, as much because the focus of our interest in cities is changing – witness the growth of the smart cities movement. So you can read the editorial here but Krugman’s essay is really the essential reading.