Archive for China

Bernoulli-IMS One World Symposium 2020 [accessible to everyone from everywhere!]

Posted in Statistics with tags , , , , , , , on June 25, 2020 by xi'an

[Since the Bernoulli-IMS meeting in Seoul had to be postponed till August 2021, the IMS, the Bernoulli society and the founding organisers of the One World webinars got together to hastily patch up a virtual substitute, resulting in this exciting event, a first on many different reality planes, with a surprisingly positive return from contacted speakers and co-organisers. The first Bernoulli-IMS meeting where the sun never sets! Free of fees and travel costs. Hopefully accessible for “everyone from everywhere”, that is, even from countries with restrictions on Internet access like China and Cuba. Or with poor broadband access.]

Join the Bernoulli Society and IMS for the first-ever, Bernoulli-IMS One World Symposium 2020 August 24-28, 2020! The meeting will be virtual with many new experimental features. Participation at the symposium is free, but registration is mandatory to get the passwords for the Zoom sessions.

Live talks by plenary speakers include Emmanuel Candes, Martin Hairer, Kerrie Mengersen, and Wendelin Werner. The symposium will also include live talks by early career speakers, prerecorded 10-minute talks with discussion sessions, posters, experimental interactive events, and problem solving sessions. Topics from probability and  mathematical statistics are arranged in 23 sessions (with 23 Zoom rooms) to which all researchers are warmly invited to contribute and discuss their original research results. Live talks will be set at two different times in order to reach the most time zones.

Accessible to Everyone from Everywhere!

ABC on COVID-19

Posted in Books, pictures, Statistics, Travel with tags , , , , , , , , on March 20, 2020 by xi'an

The paper “The effect of travel restrictions on the spread of the 2019 novel coronavirus (COVID-19) outbreak”, published in Science on 06 March by Matteo Chinazzi and co-authors, considers the impact of travel restriction in Wuhan on the propagation of the virus. (Terrible graph by the way since the overall volume of traffic dropped considerably after the ban.)

“The travel quarantine of Wuhan delayed the overall epidemic progression by only 3 to 5 days in Mainland China, but has a more marked effect at the international scale, where case importations were reduced by nearly 80% until mid February.”

They use a SLIR (susceptible-latent-infectious-removed) pattern of transmission, along with a travel flow network based on 2019 air and ground travel statistics, resorting to ABC for approximating the posterior distribution of the basic reproductive number. It is however unclear to me that the model is particularly accurate at the levels of the transmission pattern (which now seems to occur much earlier than when the symptoms appear) and of the detection rates (which vary greatly from one place to another).

ISBA in Kunming postponed till 2021

Posted in Statistics with tags , , , , , , , , , , on February 22, 2020 by xi'an

The ISBA Program committee has just announced that the ISBA World Meeting 2020 in Kunming, China, is postponed until 2021, 28 June till 03 July (and the resolution of the nCoV epidemics). Which is quite unfortunate given the closeness of the meeting and the degree of preparation of the local and scientific committees, but also unavoidable given the difficulties and reluctance of traveling to China at the moment. Hopefully, the health threat will get under control (other than keeping every citizen under lock) sooner than that. Satellite meetings like BAYSM will be moved as well, in a place and on a date soon to be announced.

As an aside, I still call for the additional organisation of mirror conferences of this World meeting  to multiply the opportunities for gathering Bayesians, share results, listen to talks and decrease the amount of travelling (and potential issues with visa, funds, human right concerns, &tc.) To quote Chairman Mao, let a hundred flowers bloom, let a hundred schools of thought contend!

SMC on the 2019-2020 nCoV outbreak

Posted in Books, R, Statistics, Travel with tags , , , , , , , , , , on February 19, 2020 by xi'an

Two weeks ago, Kurcharski et al., from the CMMID nCoV working group at the London School of Hygiene and Tropical Medicine, published on medrXiv a statistical analysis via a stochastic SEIR model of the evolution of the 2019-2020 nCoV epidemics, with prediction of a peak outbreak by late February in Wuhan and a past outbreak abroad. Here are some further details on the modelling:

Transmission was modelled as a geometric random walk process, and we used sequential Monte Carlo to infer the transmission rate over time, as well as the resulting number of cases and the time-varying reproduction number, R, defined as the average number of secondary cases generated by a typical infectious individual on each day.
To calculate the likelihood, we used a Poisson observation model fitted jointly to expected values based on three model outputs. To calculate the daily expectation for each Poisson observation process, we converted these outputs into new case onset and new reported cases inside Wuhan and travelling internationally. We assumed a different relative reporting  probability for Wuhan cases compared to international cases, as assumed only a proportion of confirmed Wuhan cases had known onset dates (fixed at 0.15 based on available line list data). As destination country was known for confirmed exported cases, we used 20 time series for cases exported (or not) to most at-risk countries each day and calculated the probability of obtaining each of these datasets given the model outputs. International onset data was not disaggregated by country and so we used the total daily exported cases in our Poisson probability calculation.
I did not look much further into the medrXiv document but the model may be too simplistic as it does not seem to account for the potential under-reporting within China and the impact of the severe quarantine imposed by Chinese authorities which may mean a new outbreak as soon as the confinement is lifted.

sustainable workshops and conferences

Posted in Kids, pictures, Statistics, Travel, University life with tags , , , , , , , , on February 17, 2020 by xi'an

The current uncertainty about whether or not ISBA 2020 will take place (and where it will take place), along with a recent Nature article and a discussion in the common room of the Department of Statistics at Warwick, lead me to renew the call for a more sustainable form of conferencing. By creating a network of local havens or a garland of local magnets (competition open for a catchy “x of local y” denomination) attracting people in the area to gather together, attend some of the video-ed talks in the other knots, and add their own local activities, from talks to collaborative brainstorming. Obviously, this requires additional planning and some technical details, but it should become a habit rather than the exception. ABC in Grenoble is thinking about it, let me know if you are interesting in creating a local image of the workshop.