València 9 snapshot [1]

Last morning, I attended the talks of Michael Goldstein and Herbie Lee, which were very interesting from very different perspectives. Michael talked about computer models, like the climate models that have been so much attacked recently for being “unrealistic”. The difficulty is obviously in dealing with the fact that the model is incorrect, what Michael calls external uncertainty. As statisticians, we are trained to deal with internal uncertainties, i.e. those conditional on the model. Michael did not propose a generic solution to this difficult problem, but he presented a series of principles towards this goal and his paper in the proceeedings (I have not [yet] read) contains examples of conducting this assessment. (I am not sure building a [statistical] model on top of the current [physical] models stands a chance to convince climato-skeptics, but this is interesting nonetheless.) Herbie addressed a completely different problem, namely the maximisation of a function under constraints when the constraints are partly unknown. (Think of a set whose boundaries are not precisely known.) This was a problem new to me and I plan to read the paper asap, as the design perspective added to the maximisation per se is made in order to decide about the worth of making new [costly] evaluations of the function to maximise.

Otherwise, the morning was spent in a fruitless pursuit of a wireless connection in the hotel where the conference takes place, as so many people were trying to connect at the same time! I eventually resolved the issue by crossing the road to an internet café and renting an ethernet cable for one hour. The hotel is unsurprisingly the soulless and unhelpful place I expected and I do not find any appeal in the high rise landscape constituting the neighbourhood. There is however a small track in the bush nearby that makes for a good running place in the early morning. (Finding a cliff that is both bolted and in the shade is going to prove a challenge!)