My vote for phrase of the year is “once-in-a-hundred years’” as a modifier to some noun. A quick search of the internet shows common usage of “one-in-a-hundred years” in reference to the pandemic, fiscal crisis, floods, forest fires, rain storms, hurricanes/typhoons, crop loss, and drought. But also, “once-in-a-hundred-year” transformation of the automobile industry, new Lamborghini model, appearance of agave flowers, and sightings of bamboo blossoms.
Of some note is the quotation of a resident of Australia, subjected to repeated floods, one after another: “It’s once in a hundred years … four weeks later we’re back.”
I’m a little worried that attached to the “one in a hundred years” moniker are some risks for all of us. It breeds either explicit or implicit excuses for inaction. “Don’t blame me, I couldn’t have predicted it.” “It would have been imprudent to prepare for this, the odds of it happening were so low.” “It won’t happen again for another 100 years; we don’t have to prepare for another event like this.” “We just need to get through this, then things will go back to normal.”
Bayesian statistical thinking allows one to utilize in a formal way all prior information about a phenomenon in order to integrate new data about it. It has value when there is a deep set of prior data speaking to the statistical question at hand. But it’s also a way of thinking about our current knowledge and deserved confidence about it. When a new finding is made, our confidence in it is a stronger if it is in agreement with prior discoveries. If a very unusual finding is obtained, it garners more skepticism. All this makes common and statistical sense.
So, how does Bayesian thinking apply to what we’re all experiencing? What are our prior data on the phenomena we’re all observing? We know that many of the phenomena have very rarely occurred. For that reason, we view these events as rare events. Our prior beliefs are shaped by the infrequency of the events.
This thinking needs a higher level of sophistication to protect us. If none of the causes of the phenomena in question have changed, using our prior knowledge is wise. If the causes of the phenomena have changed, it may be dangerous. In short, what if the causes of these rare events have radically altered the frequency of their consequences.
I’ve commented on potential causes of the “once-in-a-hundred-year” phenomena above: the encroachment of humans into more and more areas formerly inhabited only by nonhuman species, the warming of the globe due to human-induced activity, the instability of weather patterns, the harmful effects of globalization on inequality in many countries of the world.
It may well be unwise to think that the devastation of a global pandemic as a once-in-a-hundred-event based only on our experience without global warming, without radically increased human-nonhuman interaction, without the inequalities that limit equal access to health services. It might be better to say events like that “used to be” or were “formerly” once-in-a-hundred-year events.
With this reminder to ourselves, we may be more focused on how to make decisions of more lasting worth to humankind and the planet in general.
A hundred years ain’t what it used to be! We are all in this together.
A very interesting post, thank you. Perhaps in scale and upheaval the current SARS – 2 pandemic seems like “once in a hundred years” but it really isn’t anything new, it is called “SARS – 2” after all. SARS (the first one) hit the world over 17 years ago. For some us that’s a long time, for others it seems like only yesterday.
There is a very entertaining and accessible book with the eye catching title “The New Killer Diseases” (Levy and Fischetti, Three Rivers Press ISBN 1-4000-5275-0) that should perhaps be required reading in any general science or science policy class at any University in the world. The first chapter tells the story of SARS (the original), but if “SARS” is changed to “SARS-2” in about every other instance in the first 1/2 of the chapter, and a few names are changed (e.g. the courageous physician who desperately tried to ring the bell and then [spoiler alert] dies of the disease) it’s the same story. What is also “once in a hundred years” these days are the stunning and horrific attacks on science that we see almost daily, that help us to forget the lessons of just 17 years ago. The Scopes trial was 95 years ago (close enough) and is the only thing I learned about in a classroom when I was young that comes close to the assault on science today … an idealistic teacher was prosecuted for teaching science in a classroom. And the country went wild over it. As Santayana admonished us (a little more than a 100 years ago) “those who cannot remember the past are condemned to to repeat it”.
For additional insights about the seemingly increasing occurrence of once-in-a-hundred-years events read Genesis to Revelation. Such a read not only reveals descriptive and predictive insights, but also normative and prescriptive insights.
The spiritual law of “sow the wind and reap the whirlwind” does suggest an intensifying of so-called “once-in-a-hundred-years events” and yet there can be places and times where and when there is relative calm. Just because there is an expected upward trend, it doesn’t mean that nothing should be done at any given place and time.
Even if one doesn’t assume an increasingly frequent occurrence of “once-in-a-hundred-years” events, it would still make sense to employ game-theory to assess the expected likelihood of occurrence and expected magnitude of consequence for such events and make preparations to address such events in the order suggested by likelihood x magnitude.
Interesting! I guess 100 years he just ain’t what it used to be! Stay safe and teach well virtually. We are all in this together .