Archive for A Song of Ice and Fire

The winds of Winter [Bayesian prediction]

Posted in Kids, Statistics, University life, Books, R with tags , , , , , , , , , , on October 7, 2014 by xi'an

A surprising entry on arXiv this morning: Richard Vale (from Christchurch, NZ) has posted a paper about the characters appearing in the yet hypothetical next volume of George R.R. Martin’s Song of ice and fire series, The winds of Winter [not even put for pre-sale on amazon!]. Using the previous five books in the series and the frequency of occurrence of characters’ point of view [each chapter being told as from the point of view of one single character], Vale proceeds to model the number of occurrences in a given book by a truncated Poisson model,

x_{it} \sim \mathcal{P}(\lambda_i)\text{ if }|t-\beta_i|<\tau_i

in order to account for [most] characters dying at some point in the series. All parameters are endowed with prior distributions, including the terrible “large” hyperpriors familiar to BUGS users… Despite the code being written in R by the author. The modelling does not use anything but the frequencies of the previous books, so knowledge that characters like Eddard Stark had died is not exploited. (Nonetheless, the prediction gives zero chapter to this character in the coming volumes.) Interestingly, a character who seemingly died at the end of the last book is still given a 60% probability of having at least one chapter in  The winds of Winter [no spoiler here, but many in the paper itself!]. As pointed out by the author, the model as such does not allow for prediction of new-character chapters, which remains likely given Martin’s storytelling style! Vale still predicts 11 new-character chapters, which seems high if considering the series should be over in two more books [and an unpredictable number of years!].

As an aside, this paper makes use of the truncnorm R package, which I did not know and which is based on John Geweke’s accept-reject algorithm for truncated normals that I (independently) proposed a few years later.

A dance with dragons

Posted in Books with tags , , on October 29, 2011 by xi'an

A few weeks ago, I finished the fifth volume of George Martin, A Dance with Dragons, I had bought in Lancaster last summer but could not carry with me to the US (and onto the boat!). It reads wonderfully, just like the previous volumes, and so I wonder why it took the author so long to produce it. (He apologizes about this in the preface to the book. But does not [have to] provide reasons.) Esp. when considering that the story constitutes the “other side” of the previous volume, covering characters and regions that were omitted in the fourth book. Even though the pace is sometimes a wee slow (e.g., the coverage of Tyrion’s travel and mishaps and of his every thought!, or of Daenerys’ procrastination and hesitations), again, it is very pleasant to read. I am actually surprised at how easy it is to launch back into the complex geography and geopolitics of Martin’s universe, given the five year gap with my reading the previous volume. The important and consequential action has to wait a while, but things are moving fast by the end of the book, with surprising and permanent changes of dominance and of rulers. It is a good thing that Martin is eliminating some of his characters as it means he cannot go for ever in writing small prints about them! On another level, it is quite interesting to spot so many readers of the first volume (A Game of Thrones), in the metro and in airports, clearly generated by the TV adaptation on HBO…


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