Some basic COVID-19 mathematics

10 Apr, 2020 at 10:29 | Posted in Statistics & Econometrics | 6 Comments



  1. This video illustrates the narrow, blinkered myopic viewpoint of medics & epidemiologists.
    The video merely addresses 3 questions:
    Q1. Will the disease spread?
    Q2. How can the peak number of infected people be minimised?
    Q3. How can the number of people ever infected be minimised?
    Regarding Q2 & Q3 the speaker concludes that peak infections and total infections are minimised by by minimising the number of people coming into contact with an infectious person. This requires hand-washing and social distancing.
    This conclusion is defective from a narrowly medical viewpoint since it makes no allowance for the effects of social distancing on unemployment and social welfare and thence on physical and mental health.
    More fundamentally, the analysis is gravely deficient because it ignores government concerns beyond the narrow concerns of doctors.
    The government’s social welfare function is not simply: Medical Welfare = function of (peak infections, total infections).
    Rather Social Welfare = function of (health, unemployment, economic wellbeing, social harmony, internal and external security, etc).
    This is why we don’t lock-down economies for serious epidemics like influenza and measles. Nor should we do so for COVID-19.

  2. Lars, Sweden has seemed to take a different strategy than many other countries in trying to deal with this Covid19 problem. Do you have thoughts on this you would be willing to share? In any case- I hope you and your family stay safe and be well.

    • Sweden hasn’t imposed the kind of extraordinary lockdown orders that we have seen in many other countries. That’s true. Instead of a lockdown, we trust our citizens to take responsibility and follow social distancing guidelines. But, actually, we’re not doing things much different from what other countries in Europe do. We have a strong social capital in this country. We trust each other and take responsibility. That makes all the difference.

      • Thank you Lars. As you probably realize there is an intense debate about the ‘lockdowns’ in my country and about how useful they are given the enormous economic costs of them. Very selfishly, I was hoping that Sweden would show one way or the other whether those lockdowns were smart policy or just a giant very costly mistake. Obviously in terms of human lives it would be better that they were in fact a mistake and that Sweden does not suffer from not imposing them. But if you are saying that your fellow citizens are basically following the same protocal without it being imposed because there is a lot more social cohesion and sense of social responsibility among Swedes, then a lack of significant difference in outcome is probably not going to tell us much. Except that it will for sure be used as evidence that in the US our shutting down of significant parts of the economy was a total mistake. I myself have been supporting the temporary shutdowns until we have better data. But believe me I hope it turns out I was wrong to do so.

        I very much appreciate that you replied to my question and of course, any further thoughts or ideas would be very welcome. Thanks!

  3. Isn’t this model frightfully ergodic? The q parameter assumes one representative agent. My individual time series average is assumed to equal the population ensemble average. No allowance is made for my self-isolation outdoors not contributing to new infections. The ergodic model prescribes one solution, lockdown, for all, even though my individual q is lower than the ensemble q.

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