Friday, July 30, 2010

Communicating (Agent-Based) Models

So, you've worked hard and finally you have a working ABM, full of features and parameters and you are super-excited and want to show everybody your latest phase space or time-series. You go to a conference or you write a paper, in any case chances are that people will misunderstand your model, or will simply take for granted it's underlying algorithm and there will be very few questions...especially if your audience is not trained....
I think that one of the biggest problem archaeological (and non) ABM must face is when your model reaches it's audience and you have a small window of time (10~30 minutes) and/or space (3000~5000 words) to communicate all the algorithms and submodels you've used.  Now even in an ideal (?) word where everybody understands Java, C++ or NetLogo (or even R in my case), few people will have the patience and the willingness to go through your raw code and try to understand how really your model works. Most people, will simply look at your conclusions, or read through the old-fashioned text-based way of communicating your model. The problem then is how you evaluate other people's model. Well the short answer at this stage is that you could but you won't. And the risk is that we lose the scientific feedback process, bringing us back to simple story-telling with perhaps some fancy dynamic illustrations....
The thing is that, I'm much convinced that greatest achievement that archaeology can gain from ABM, is not the actual bunch of codes and files, but the formalisation of submodels. We tell stories and we tend often to avoid details in the non-computational modelling process. We delineate the larger trends without tackling the smallest issues. This epistemological laziness  (as one of my supervisors would call) is however strictly prohibited in an ABM. Or to better put, you can still place lazy models, but people will discover this and criticise it..but only if your model, submodels and algorithm are well communicated.
So the communication problem is really a big issue, and the risk is to be trapped with a series of over-complicated hyper-realistic models, with very long codes that nobody will ever read and check...

I'm having a series of nice chats with Yu Fujimoto, a visiting scholar from the Faculty of Culture and Information Science at the Doshisha University in Japan. The discussions are around whether models should be communicated through UMLs (Unified Modeling Language)  or using the ODD (Overview Design Concepts, and Details) Protocols advocated by Volker Grimm or simply by series of pseudo-codes. All modes of communications are around, but not common in archaeology. One reason is that a non-trained archaeologist will struggle to understand pseudo-codes, and will definitely reject UML as something mystic and unquestionably complicated. This leaves ODD, which hopefully will take over. Ideally journals should allow the upload of the source code and also an additional appendix with the ODD description of the code, leaving aims&objectives, brief description, experiments results and discussion as the core elements of the paper. Of course, having said that, the problem of model communication in conferences remains tricky, as going through the ODD will most likely use the entire time-block and you'll hear the 5 minutes bell ringing as soon as you reach the second D....


  1. Hi Enrico

    The problem of communicating what's going on in the model is one of the hardest things to do. Until the methodology gains wider acceptance, it's going to be an issue. I've found that it's far better to develop many small/simple models, than to try for one super-model that covers everything. I try to model one single concept that can then be elaborated as necessary (the morning salutatio, for instance, as a proxy for patronage relationships in Rome). I also refer folks to 'Groundhog Day' as an example of an agent model where a single agent - Phil Conners - explores all the possible behavior space in turn. That helps, to a degree.

    We might find more success explaining what we're doing at an 'unconference', rather than a more traditional one, though I don't know of any archaeological conferences adopting that model - yet.

  2. Hi Shawn,

    I guess the biggest struggle is really to "keep it simple", there is always a tendency to overcomplicate things...(it's my greatest unconscious temptation)..But I'm also concerned that when you have a modular structure of a larger multifaced-phenomena (with say 4 simulations approaching specific issues), then one should worry about how to combine them. Then again the option is to do this verbally (losing all the power of simulation models) or to create a single super-model...and we know already the problem with the latter.. Difficult...

    As far as oral presentation, I think that's a bright idea and the way to go.
    I've attended so far on two unconferences (Antiquist, and Rchaeology) and I do love the format (much more than traditional conferences, and much more feedbacks), but I guess the number of people actively engaged in ABM is still too small and above all too sparse probably..I guess there should be something within a bigger conference like CAA.