JSM 2014, Boston [#4]

Last and final day and post at and about JSM 2014! It is very rare that I stay till the last day and it is solely due to family constraints that I attended the very last sessions. It was a bit eerie, walking through the huge structure of the Boston Convention Centre that could easily house several A380 and meeting a few souls dragging a suitcase to the mostly empty rooms… Getting scheduled on the final day of the conference is not the nicest thing and I offer my condolences to all speakers ending up speaking today! Including my former Master student Anne Sabourin.

I first attended the Frontiers of Computer Experiments: Big Data, Calibration, and Validation session with a talk by David Hingdon on the extrapolation limits of computer model, talk that linked very nicely with Stephen Stigler’s Presidential Address and stressed the need for incorporating the often neglected fact that models are not reality. Jared Niemi also presented an approximative way of dealing with large dataset Gaussian process modelling. It was only natural to link this talk with David’s and wonder about the extrapola-bility of the modelling and the risk of over-fitting and the potential for detecting sudden drops in the function.

The major reason why I made the one-hour trip back to the Boston Convention Centre was however theonder about the extrapola-bility of the modelling and the risk of over-fitting and the potential for detecting sudden drops in the function.

The major reason why I made the one-hour trip back to the Boston Convention Centre was however the Human Rights Violations: How Do We Begin Counting the Dead? session. It was both of direct interest to me as I had wondered in the past days about statistically assessing the number of political kidnappings and murders in Eastern Ukraine. And of methodological relevance, as the techniques were connected with capture-recapture and random forests. And of close connections with two speakers who alas could not make it and were replaced by co-authors. The first talk by Samuel Ventura considered ways of accelerating the comparison of entries into multiple lists for identifying unique individuals, with the open methodological question of handling populations of probabilities. As the outcome of random forests. My virtual question related to this talk was why the causes for duplications and errors in the record were completely ignored. At least in the example of the Syrian death, some analysis could be conducted on the reasons for differences in the entries. And maybe a prior model constructed. The second talk by Daniel Manrique-Vallier was about using non-parametric capture-recapture to count the number of dead from several lists. Once again bypassing the use of potential covariates for explaining the differences.  As I noticed a while ago when analysing the population of (police) captured drug addicts in the Greater Paris, the prior modelling has a strong impact on the estimated population. Another point I would have liked to discuss was the repeated argument that Arabic (script?) made the identification of individuals more difficult: my naïve reaction was to wonder whether or not this was due to the absence of fluent Arabic speakers in the team. Who could have further helped to build a model on the potential alternative spellings and derivations of Arabic names. But I maybe missed more subtle difficulties.

One Response to “JSM 2014, Boston [#4]”

  1. Dan Simpson Says:

    One of those is pretty easy: Gaussian processes can’t model functions with sudden drops. They tend to concentrate on Hölder and L2 Sobolev spaces, which don’t allow piece wise continuous functions

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