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katastrofa
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Re: How good or bad are the pandemic warning models?

February 12th, 2020, 2:44 am

Is R0 reproductive ratio? I don't know what's for Covid-19 (I don't like the name, too similar to Corvids), but SARS had 2-5.

@"calculations on cocktail napkins"
That was Banach - brilliant mathematician, but sometimes feeding ground for lice. Life.

@"I never call him Fibonacci,.. his name is Leonardo of Pisa."
I called him the most celebrated Western Medieval mathematician - for translating Islamic thinkers' scripts ;-P
 
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Cuchulainn
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Re: How good or bad are the pandemic warning models?

February 12th, 2020, 8:41 am

Indeed, Leonardo' dad used to bring him on sailing trips to Algeria where he learned Arabic number system.

Fibonacci numbers (and pi) are silly. Polynomials are cooler.

https://en.wikipedia.org/wiki/Fibonacci_polynomials
http://www.datasimfinancial.com
http://www.datasim.nl

Every Time We Teach a Child Something, We Keep Him from Inventing It Himself
Jean Piaget
 
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tw
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Joined: May 10th, 2002, 3:30 pm

Re: How good or bad are the pandemic warning models?

February 12th, 2020, 1:40 pm

In SIR the Rs are both dead and recovered+immune I.e. can’t cause any more infections. In going from R to number dead is the easy bit!

You need SIR plus a transition matrix for travel between airports plus diffusion in space. It’s just a credit risk model!

Corid19 low mortality but long quarantine

Black Death is extremely high mortality and short quarantine (I think)

Not the end of the world yet.

Get Jim Murray’s books! All the details are there. They’re quite big. And you can always throw them at anyone who is coughing near you.
Thanks for the book recommendation. I try to be disciplined buying fat springer books that I end up only reading small sections of but
I usually give in for such diverse and fascinating material.

I must say I love the research topics on Murray's webpage:
Other areas of current research are: (i) modelling marital interaction and divorce prediction and the development of a scientifically based marital therapy; (ii) benefits of cannibalism; (iii) specific species extinction which could result from climate change, specifically mild temperature rise.
Now they are research topics to get one's teeth into! Especially (ii)

I am rather intrigued that that SIR has an analytic solution albeit not an easy one.  Before digging into micro structure, I wonder if
one can solve the basic model with simple time-dependent parameters (R0 particularly) to describe improving policy responses to the
the epidemic to see if there is some critical level you need to get to (and how fast) to nip it in bud.
 
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Paul
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Re: How good or bad are the pandemic warning models?

February 12th, 2020, 4:11 pm

This should never have been a Springer book. Springer books are awful. Their only redeeming feature is that being yellow you can see them from a long way away. My old edition of JM's book is a nice green though.

Before getting into time dependence I would recommend doing a nondimensionalization. Just to see what the relevant non-dim quantities are, and how many. That's what I was hinting at in the mentions of covid-19 and the Black Death. 

The models in this field are usually fairly easy to understand. (Math biology involving hardcore biochem is another matter!)
 
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katastrofa
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Re: How good or bad are the pandemic warning models?

February 12th, 2020, 5:25 pm

I am rather intrigued that that SIR has an analytic solution albeit not an easy one.  Before digging into micro structure, I wonder if
one can solve the basic model with simple time-dependent parameters (R0 particularly) to describe improving policy responses to the
the epidemic to see if there is some critical level you need to get to (and how fast) to nip it in bud.
Why be surprised? It's just a bunch of simple differential equations.
SIR is for diseases with lifelong immunity, that's why it's used to design vaccination programs (re improving policies).

I actually wrote a microsimulation model of an Internet worm spreading in a computer network to evaluate the cybersecurity threat and design prevention strategies... But now I have to go back to my craft beer :-)
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Collector
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Re: How good or bad are the pandemic warning models?

February 12th, 2020, 7:07 pm

how are those apartment complexes that use centralized internal  recycling of some of the air to save energy suited for Covid-19 ?
 
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Paul
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Re: How good or bad are the pandemic warning models?

February 12th, 2020, 7:12 pm

It's a simple change of parameter!
 
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Paul
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Re: How good or bad are the pandemic warning models?

February 12th, 2020, 11:25 pm

The Dalai Lama has cancelled events in response to Covid19. 

Is this peak hysteria? If it is then that probably coincides with peak death rate.
 
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trackstar
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Re: How good or bad are the pandemic warning models?

February 12th, 2020, 11:35 pm

The Dalai Lama has cancelled events in response to Covid19. 

Is this peak hysteria? If it is then that probably coincides with peak death rate.
I am not a hysterical kind of person, but we all should be paying attention - don't believe the hype, but do read between the lines...

Top CDC official says US should prepare for coronavirus ‘to take a foothold - CNBC Feb 12

In particular, here are two issues: one patient in a San Diego hospital was released by mistake and there have been more than 30,000 travellers to the US from China since mid-Jan.  The CDC has been monitoring them, but it is complicated.

"The CDC said Tuesday that a mistake at a lab led U.S. health officials to release an infected coronavirus patient from a San Diego hospital. The patient had been evacuated from Wuhan, the epicenter of the outbreak, on a government-chartered flight last week.

Messonnier said Wednesday that U.S. health officials are implementing “additional quality controls” to ensure another patient is not misidentified again.
Additionally, the CDC has monitored since mid-January more than 30,000 travelers coming to the U.S. from China. They have not detected any cases from returning travelers. Health officials are asking the travelers to monitor their own symptoms and limit their outdoor activities, Messonnier said."

My policy remains - do what is necessary in terms of errands and work, but also take advantage of this quasi self-quaratine time to do early spring cleaning around the house. There is always more to do!  And I made another quilt. : )
Last edited by trackstar on February 12th, 2020, 11:36 pm, edited 1 time in total.
 
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Paul
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Re: How good or bad are the pandemic warning models?

February 12th, 2020, 11:36 pm

Spot which of the below are not seeking more funding:
 I hope this outbreak may be over in something like April

Prof. Nanshan Zhong

Leading epidemiologist, first to describe SARS coronovirus
Feb. 11, 2020
 It could infect 60% of global population if unchecked

Prof. Gabriel Leung

Expert on coronavirus epidemics
Chair of Public Health Medicine
Hong Kong University
Feb. 11, 2020
 It’s a new virus. We don’t know much about it, and therefore we’re all concerned to make certain it doesn’t evolve into something even worse

Prof. W. Ian Lipkin

Epidemiology Director
Columbia University
Feb. 10, 2020
 We are estimating that about 50,000 new infections per day are occurring in China. [...] It will probably peak in its epicenter, Wuhan, in about one month time; maybe a month or two later in the whole of China. The rest of the world will see epidemics at various times after that. (EXPAND FOR VIDEO)

Prof. Niall Ferguson

Director, Institute for Disease and Emergency Analytics (J-IDEA)
Imperial College, London Feb. 6, 2020
 This looks far more like H1N1’s spread than SARS, and I am increasingly alarmed

Dr. Peter Piot

(Director, The London School of Hygiene and Tropical Medicine)
Feb. 2, 2020
 It sounds and looks as if it’s going to be a very highly transmissible virus [...] This virus may still be learning what it can do, we don’t know its full potential yet.

Robert Webster

(Infectious disease and avian flu expert at St. Jude Children’s Research Hospital)
Feb. 2, 2020
 Increasingly unlikely that the virus can be contained

Dr. Thomas R. Frieden

(Former Director of CDC)
Feb. 2, 2020
 It’s very, very transmissible, and it almost certainly is going to be a pandemic. But will it be catastrophic? I don’t know 

Dr. Anthony S. Fauci

(Director, National Institute of Allergy and Infectious Disease)
Feb. 2, 2020
 Until [containment] is impossible, we should keep trying

Dr. Mike Ryan

(Head of the WHO’s Emergencies Program)
Feb. 1, 2020
 The more we learn about it, the greater the possibility is that transmission will not be able to be controlled with public health measures

Dr. Allison McGeer

(Director of Infection Control, Mount Sinai Hospital, Toronto)
Jan. 26, 2020
 
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trackstar
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Joined: August 28th, 2008, 1:53 pm

Re: How good or bad are the pandemic warning models?

February 12th, 2020, 11:42 pm

Spot which of the below are not seeking more funding:
Sure, that also has to be factored in to how you read the news. But even given some cynical assumptions about the expert commentators, it still does not mean everything will be fine in 24 days or less.  Don't worry - throw a Covid-19 party!

I can keep a significant amount of very conflicting information in my head for long periods of time without obsessing over WHAT IS THE REALITY. You just have to keep reading, watching and see. : )  

Can you folks do that?, If so, why? And if not, what happens next?

What is the most advanced precaution I have taken?, you may ask, Well, it is nice to have 20+ cases of water (in *plastic* bottles, oh the horror. LOL) in my basement while observing the world as it turns.  

You may have heard, "40 days till you starve." But water - 3 days to a week and you are done.

Finally, here is something that makes me laugh a little, but I do feel badly for people who are worried about this aspect:

Home Depot - Search Masks

Just about every kind of mask - "Delivery unavailable. Limited stock in nearby stores."  

Seriously, people. Stocking up on hundreds and hundreds of nuisance masks is not going to be that helpful.

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Collector
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Re: How good or bad are the pandemic warning models?

February 13th, 2020, 8:52 am

 
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Collector
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Joined: August 21st, 2001, 12:37 pm

Re: How good or bad are the pandemic warning models?

February 13th, 2020, 10:21 am

The largest coronavirus outbreak outside mainland China is not in a country, but on a cruise ship.

I wonder if it can be any relation to centralized re-circulation of air? or just much people in small space...

"In mechanical ventilation and air-conditioning systems, recirculation of air is used to control temperature and air distribution and to is recirculated back to the supply airflow which is a mixture of return air and outdoor air.  In this type of ventilation system, apart of the exhaust air from the rooms (return air) is recirculated back to the supply airflow, which is a mixture of return air and outdour air.

Proportions of recycled air as high 80% to 90% of recycled air is common in North America, wheres finland they are normally between 30% to 70%."

https://ajph.aphapublications.org/doi/pdf/10.2105/AJPH.84.3.422

I assume this invention of centralized re-cycled air in appartment complexes is to save energy (and save the earth from global warming?). 

And remember to wash and dry your dirty hands! In particular in public places use the new super effective hand dryers that are excellent because u do not need to touch anything, and therefore dramatically reduces risk of exposure to others: Dyson Airblades 'spread germs 1,300 times more than paper towels'
Last edited by Collector on February 13th, 2020, 11:56 am, edited 1 time in total.
 
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tw
Posts: 1173
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Re: How good or bad are the pandemic warning models?

February 13th, 2020, 11:36 am

Why be surprised? It's just a bunch of simple differential equations.
SIR is for diseases with lifelong immunity, that's why it's used to design vaccination programs (re improving policies).

Intrigued, not surprised. Since, in the basic model , the quantity I (the #infected) multiplies each term, the epidemic equilibrium
has that equal to zero but the others variables are in some sense degenerate/undetermined.

However, clearly an equilibrium solution exists, but to get it you have to solve the dynamics, rather than searching for equilibrium points. 
The T->infty levels for S and R are the solutions of those transcendental equations, (that I was looking for an approx for, to see how many of us are going to drop dead of this thing,  at least in one version of the theory!)

Solutions that involve transforming a system of ODEs to get to a Bernoulli or Riccati equation, (like this one), I always find a bit magical.
They cropped up for me years back in mechanics. If you make any minor sounding changes in the system (e.g. time dependent parameter)
the whole solution technique falls apart, which makes me wonder what is "special" about this configuration.




I actually wrote a microsimulation model of an Internet worm spreading in a computer network to evaluate the cybersecurity threat and design prevention strategies... But now I have to go back to my craft beer :-)
Somehow craft beer always reminds me of Aubrey de Grey's method to live forever!  :)
 
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tw
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Joined: May 10th, 2002, 3:30 pm

Re: How good or bad are the pandemic warning models?

February 13th, 2020, 11:40 am

We will all be like Dr Rieux soon.



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