Saturday, March 21, 2020

Exponential vs

Pearl curve


It starts out looking like exponential growth, and then flattens out as whatever-it-is saturates. WRT the Wuhan virus, we're at the start of the curve, where things look like exponential growth.

I'm just being picky, here. And, for those not aware, "exponential" doesn't always mean growing--it can mean shrinking too.

(To my relief but not surprise, I tested negative and don't have to self-isolate anymore. It turns out that has an impact on what other members of the household are allowed to do. But I've still got a bad cold.)


For some reason newspaper explanations remind me of this.

Two mathematicians are in a bar. The first one says to the second that the average person knows very little about basic mathematics. The second one disagrees, and claims that most people can cope with a reasonable amount of math.

The first mathematician goes off to the washroom, and in his absence the second calls over the waitress. He tells her that in a few minutes, after his friend has returned, he will call her over and ask her a question. All she has to do is answer "one third x cubed."

She repeats "one thir -- dex cue"?
He repeats "one third x cubed".
She asks, "one thir dex cuebd?"
"Yes, that's right," he says.
So she agrees, and goes off mumbling to herself, "one thir dex cuebd...".

The first guy returns and the second proposes a bet to prove his point, that most people do know something about basic math. He says he will ask the blonde waitress an integral, and the first laughingly agrees. The second man calls over the waitress and asks "what is the integral of x squared?".
The waitress says "one third x cubed" and while walking away, turns back and says over her shoulder "plus a constant!"

4 comments:

Anonymous said...

Its generally agreed among those who specialize in pandemics, that the infection rate will double about every 6 days in a community. That's "exponential".

That is what is most probably what is happening in your country, and by calculations done weeks ago, your medical system should collapse by the end of April.

Jonathan said...

The mathematical ignorance of journalists is terribly costly to the society as a whole.

james said...

Yes. Statistics is another field where the ignorance of the policy-makers and policy-movers causes grief and waste.
"A little learning is a dangerous thing"--they partly understand a summary, and take their extrapolation for gospel.

Assistant Village Idiot said...

I have advocated that statistics and probabilities would be a more useful highschool math than the current system which seems more designed to identify the gifted than inform the general populace. Algebra II is an excellent break point for identifying who, even among the less-mathematically-inclined, can think abstractly. (Bright abstract thinkers that are more verbal can at least hang on that far.) But the design of Algebra I and Geometry are lead-ins to that, not so useful in themselves. Practical math can include portions of this, but the percentage of people who will need to know side-angle-side is small. The percentage who will need to understand how statistics are presented and how probabilities are calculated is much larger.