Blog posts

Great Barrington Declaration

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I have just signed the Great Barrington Declaration.

My unpublished COVID-19 paper is now my most cited paper

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Recently, my working paper Susceptible-Infected-Recovered (SIR) Dynamics of COVID-19 and Economic Impact has surpassed my JEBO paper in terms of citation counts, and has become my most cited paper. My COVID-19 paper is one of the very first written by an economist on this topic, and it appeared in the first issue of the working paper series Covid Economics. Although I am no longer working on this paper since the situation with COVID-19 has been changing too quickly (especially when I wrote the paper in March 2020) to keep up with, I am glad that this paper has made some impact. In fact, it was featured in VoxEU and Fortune articles.

Berkeley banning junk food in checkout aisles is nonsense paternalism

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As a long-time California resident, I am very well aware of all those government red tapes. But the recent move of the city of Berkeley to ban placing junk food and beverages at checkout ailes is completely nonsense.

Inequality on spectral abscissa

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Let $A, B$ be square (complex) matrices such that $|B| \le A$. Then it is well known that $\rho(B) \le \rho(|B|) \le \rho(A)$, where $\rho$ denotes the spectral radius (largest absolute value of all eigenvalues). See, for example, Theorem 8.4.5 of Horn and Johnson (2013). In my recent paper, we needed to use the spectral abscissa (largest real part of all eigenvalues) instead of the spectral radius. By analogy, we can make the following conjecture: if $A, B$ are square complex matrices such that $\mathrm{Re} b_{nn} \le a_{nn}$ for all $n$ and $|b_{nn’}| \le a_{nn’}$ for all $n \neq n’$, then is it true that $\zeta(B) \le \zeta(A)$, where $\zeta$ denotes the spectral abscissa?