Archive for IMS
Bayesian score calibration at One World ABC’minar [only comes every 1462 days]
Posted in Books, Statistics, University life with tags ABC, Approximate Bayesian computation, approximate Bayesian inference, approximate models, Bayesian calibration, IMS, leap year, One World ABC Seminar, seminar, University of Warwick, webinar on February 22, 2024 by xi'an
how many migrants died trying to reach Europe?
Posted in Books, Kids, pictures, Statistics, Travel, University life with tags Annals of Applied Statistics, capture-recapture, death at sea, Europe, Frontex, IMS, Mediterranean Sea, migrations, refugees, Syrian civil war, United against Racism, Università di Roma Tor Vergata on February 6, 2024 by xi'an
“We estimated that about 40,000 human beings have died trying to enter the European Union, during about 5500 tragic attempts, in the period between January 1993 and March 2019.”
A paper by Alessio Farcomeni published last year in Annals of Applied Statistics [that is delivered to me by regular mail, but which I missed] about estimating the number of deaths on migration routes. I have been interested in this question for moral and statistical reasons since the beginning of the Syrian civil war and the induced massive increase in the number of people attempting to cross the Mediterranean Sea to reach Europe. Unfortunately, despite different attempts to contact governmental agencies (like the French Minister of the Interior), NGOs (like Amnesty), friends, academics (incl. a Dutch group on that very topic but with no data or data scientist), and connections (with the Italian Navy, the Tunisian government and Frontex), I could not access more than newspaper level data or highly local data that did not allow for a general picture.
“The law of large numbers guarantees consistency as long as the population size estimator is consistent and the model is well-specified.”
As it was my intention, the paper uses capture-recapture. The data is obtained from UNITED for Intercultural Action. It had recorded 4333 attempts to enter Europe that had at least one death occurring, between January 1993 and March 2019, as reported by one or several sources, like newspaper articles. Sources that are most often not independent, but rather copying one another, which is obviously problematic for the extrapolation to the unreported cases and for resorting to capture-recapture estimation. And the number of deaths per event is itself most likely inexact, since casualties are not always recovered or identified as such. Since migration routes, migrant flows, and smuggler policies keep massively changing, the homogeneity of the observations over nearly 30 years is low to inexistent, which makes invoking consistency rather inappropriate. This is also the reason why I find the approach followed by the paper too strongly model-based as for instance when relying on an Horvitz-Thompson estimator or using a GLM to link the number of deaths in one crossing and the number of sources reporting the tragedy. This fundamental difficulty in modelling or inferring from such unreliable and untrustworthy data sources and the absence of record linkage with other datasets like the entries in the border countries (e.g., Turkey) or the number of prevented crossings by the local coastguards alas make the final estimate of 40,000 deaths at sea close to impossible to calibrate from a model-free perspective. The actual figure is not only higher, but maybe considerably so. Unfortunately, the datasets that would allow linkage and recapture are unavailable or inexistent in departure countries, while arrival countries most abstain from storing data about the migrant flows and histories…
IMS Carver Award 2023
Posted in Books, pictures, Statistics, Travel, University life with tags Bernoulli society, IMS, IMS Carver Medal, Institute of Mathematical Statistics, Leif Döring, One World Bernoulli IMS conference on July 6, 2023 by xi'an
in defense of subjectivity [sound the gong]
Posted in Books, Statistics, Travel, University life with tags Friedrich Nietzsche, Henri Poincaré, IMS, IMS Bulletin, Keep calm posters, Krzysztof Burdzy, London, London calling, Montréal, presidential address, Rutgers University, subjective versus objective Bayes, The Clash on October 13, 2022 by xi'an
When browsing the IMS Bulletin [01 October] a few days ago, I saw that Ruobin Gong (from Rutgers) had written a tribune about Subjectivism. In response to [IMS President] Krysz Burdzy’s presidential address at the IMS Meeting in London a few months earlier. Address that I had missed and where he was calling for the end of the term subjective in statistics… (While ironically attending the Bayesian conference in Montréal!) Given the tone of his Search for Certainty book, which Andrew and Larry and I discussed a while ago, I am not at all surprised by another go at Bayesian statistics, but I will not indulge into another response, since Krysz found my earlier review “venomous”! Especially since Ruobin has produced a deeply argument ed and academically grounded criticism of the presidential address (which, if I may mention it, sounds rather rambling away from statistics). In particular, Ruobin introduces Objectivity³ as “an interpreted characterization of the scientific object”, which reminds me of Nietzsche’s aphorism about physics. And where personal and collegial inputs are plusses, even though they could be qualified to be “subjective”. This was also Poincaré’s argument for Bayesian reasoning. In conclusion, I think that the London call to cease using the term in statistics was neither timely (as the subjective-versus-objective debate has sort of dried out) nor appropriate (in that it clashed with the views of part of the IMS community).
IMS conFlorence [ICSDS2022]
Posted in pictures, Statistics, Travel, University life with tags conference, Firenze, Florence, IMS, Institute of Mathematical Statistics, Italy, North America, Tuscany on April 18, 2022 by xi'an
The IMS is launching a new conference series, the annual IMS International Conference on Statistics and Data Science (ICSDS), whose goal is to reach out and expand membership from emerging areas of data science, underrepresented groups, and from regions outside of North America, first edition is next December (13-16) in Firenze (Florence), Italy. (And which I plan to attend.) Reposted from the conference web page:
The objective of ICSDS is to bring together researchers in statistics and data science from academia, industry and government in a stimulating setting to exchange ideas on the developments of modern statistics, machine learning, and broadly defined theory, methods and applications in data science.
The conference will consist of plenary sessions, and about 50 invited, contributed and poster sessions. Young researchers are particularly encouraged to participate, as a portion of the invited sessions will be designated for young researchers.
