Yet another workshop around! Still at Warwick, organised by Simon Barthelmé, Nicolas Chopin and Adam Johansen on the theme of statistical aspects of neuroscience. Being nearby I attended a few lectures today but most talks are more topical than my current interest in the matter, plus workshop fatigue starts to appear!, and hence I will keep a low attendance for the rest of the week to take advantage of my visit here to make some progress in my research and in the preparation of the teaching semester. (Maybe paradoxically I attended a non-neuroscience talk by listening to Richard Wilkinson’s coverage of ABC methods, with an interesting stress on meta-models and the link with computer experiments. Given that we are currently re-revising our paper with Matt Moore and Kerrie Mengersen (and now Chris Drovandi), I find interesting to see a sort of convergence in our community towards a re-re-interpretation of ABC as producing an approximation of the distribution of the summary statistic itself, rather than of the original data, using auxiliary or indirect or pseudo-models like Gaussian processes. (Making the link with Mark Girolami’s talk this morning.)
Archive for neurosciences
statistical challenges in neuroscience
Posted in Books, pictures, Statistics, Travel with tags ABC, computer experiment model, Gaussian processes, indirect inference, neurosciences, University of Warwick, workshop on September 4, 2014 by xi'anLe Monde puzzle [#869]
Posted in Books, Kids, Statistics, University life with tags big data, Cogent, Collège de France, dark matter, Le Monde, mathematical puzzle, Matthieu Ricard, neurosciences, religions, social sciences on June 8, 2014 by xi'anAn uninteresting Le Monde mathematical puzzle:
Solve the system of equations
- a+b+c=16,
- b+c+d=12,
- d+c+e=16,
- e+c+f=18,
- g+c+a=15
for 7 different integers 1≤a,…,g≤9.
Indeed, the final four equations determine d=a-4, e=b+4, f=a-2, g=b-1 as functions of a and b. While forcing 5≤a, 2≤b≤5, and 7≤a+b≤15. Hence, 5 possible values for a and 4 for b. Which makes 20 possible solutions for the system. However the fact that a,b,c,d,e,f,g are all different reduces considerably the possibilities. For instance, b must be less than a-4. The elimination of impossible cases leads in the end to consider b=a-5 and b=a-7. And eventually to a=8, b=3… Not so uninteresting then. A variant of Sudoku, with open questions like what is the collection of the possible values of the five sums, i.e. of the values with one and only one existing solution? Are there cases where four equations only suffice to determine a,b,c,d,e,f,g?
Apart from this integer programming exercise, a few items of relevance in this Le Monde Science & Medicine leaflet. A description of the day of a social sciences worker in front of a computer, in connection with a sociology (or sociometry) blog and a conference on Big Data in sociology at Collège de France. A tribune by the physicist Marco on data sharing (and not-sharing) illustrated by an experiment on dark matter called Cogent. And then a long interview of Matthieu Ricard, who argues about the “scientifically proven impact of meditation”, a sad illustration of the ease with which religions permeate the scientific debate [or at least the science section of Le Monde] and mingle scientific terms with religious concepts (e.g., the fusion term of “contemplative sciences”). [As another “of those coincidences”, on the same day I read this leaflet, Matthieu Ricard was the topic of one question on a radio quizz.]
Le Monde puzzle [#845]
Posted in Books, Kids, Statistics with tags Académie des Sciences, Escher, France Culture, James Joyce, Katrin, Le Monde, Lewis Carroll, mathematical puzzle, neurosciences, neutrino, quark on December 21, 2013 by xi'anYet another one of those Le Monde mathematical puzzles which wording is confusing to me:
Take the set of integers between 1 and 1000. endow all of them randomly with red or blue tags. group them by subsets of three or more (grapes). and also group them by pairs so that a switch can change the colour of both integers. Is it always possible to activate the switches so that one ends up with all grapes being multicoloured? Unicoloured?
I find it (again!) ultimately puzzling since there are configurations where it cannot work. In the first case, take a grape made of four integers of the same colour, reunited two by two by a switch: activating the switch simply invert the colours but the grape remains uni-coloured. Conversely, take two integers with opposite colours within the same grape. No mater how long one operates the switch, they will remain of an opposite colour, won’t they?!
This issue of Le Monde Science&Médecine leaflet actually had several interesting entries, from one on “the thirst of the sociologist for statistical irregularities“—meaning that regression should account for confounding factors like social class versus school performances—to the above picture about weighting the mass of a neutrino—mostly because it strongly reminds of Escher, as I cannot understand the 3D structure of the picture—, to another tribune of Marco Zito informing me that “quark” is a word invented by James Joyce—and not by Carroll as I believed—, to an interview of Stanislas Dehaene, a neuroscientist professor at Collège de France and a (fairly young) member of the Académie des Sciences—where he mentions statistical learning patterns that reminded me of the Bayesian constructs Pierre Bessière discussed on France Culture—.
Bayesian introductions at IXXI
Posted in Mountains, Statistics, Travel, University life with tags ABC, Bayesian statistics, causality, Grenoble, history of statistics, neurosciences, population genetics on October 28, 2013 by xi'an
It was supported by IXXI, Rhône Alpes Complex Systems Institute, a light structure that favors interdisciplinary research to model complex sytems such as biological or social systems, technological networks… This was an opportunity to recycle my Budapest overview from Bayes 250th to Bayes 2.5.0. (As I have changed my email signature initial from X to IX, I further enjoyed the name IXXI!) More seriously, I appreciated (despite the too short time spent there!) the mix of perspectives and disciplines represented in this introduction, from Bayesian networks and causality in computer science and medical expert systems, to neurosciences and the Bayesian theory of mind, to Bayesian population genetics. And hence the mix of audiences. The part about neurosciences and social representations on others’ mind reminded me of the discussion with Pierre Bessières we had a year ago on France Culture. Again, I am quite sorry and apologetic for having missed part of the day and opportunities for discussions, simply because of a tight schedule this week…
