## Wednesday, June 23, 2021

### What’s the purpose of mathematical modeling? — Andrew Gelman

And it has this good quote:

Scientists — not just in epidemiology, but in physics, ecology, climatology, economics and every other field — don’t build models as oracles of the future. For them, a model “is just a way of understanding a particular process or a particular question we’re interested in,” Kucharski said, “and working through the logical implications of our assumptions.”
Statistical Modeling, Causal Inference, and Social Science
What’s the purpose of mathematical modeling?
Andrew Gelman | Professor of Statistics and Political Science and Director of the Applied Statistics Center, Columbia University

NeilW said...

The purpose of mathematical modelling has the same purpose as the rituals in a seance. To increase the belief in those who want to believe.

Stories matter because people believe them, not because they are true.

Throughout human history those who have been able to marshall human belief are the ones that determine the direction of society.

Peter Pan said...

I don't care what my teachers say
I'm gonna be a mathematical supermodel.
Everyone is gonna dress like me,
Everyone wants to look like me,
Cos I'm a mathematical supermodel.

Matt Franko said...

Whoa: “ I fear that, in this and other countries, there is an implicit assumption that a primary goal of public health is to form a protective ring around institutionalized health resources.”

lastgreek said...

What's the purpose of mathematical...

Oh wow! That's my cue :)

So, because I need to get online soon and buy my mother a ceramic hairbrush holder, I'll get straight to the intersting point:

One of the most fascinating topics in mathematics is imaginary (complex) numbers. I don't care for the name because it makes them sound lik the numbers are not important. But nothing could be further from the truth! Actually, without the use of imaginary numbers the field of mathematics (hell, you can forget about quantum physics [snicker]) would still be, relatively speaking, in the Dark Ages.

Definition of "i" (imaginary number):

i = the square root of [are you ready for this?!] -1.

All through grade school and high school kids are told that their is no solution for the square root of negative number. Well, guess what? That holds true when you are dealing ONLY with real numbers. So, yeah, there is no real solution for, say, the square root of negative 25. All of the numbers that you people have been exposed to your entire lives are what mathematicians call "real numbers": positive numbers, negativie numbers, rational numbers (that just a fancy-dandy way of saying "fractions"), irrational numbers (think of pi, square root of 2: numbers with non-repeating decimals that go on forever). So what do you think the mathematicians did to solve equations that have square roots with negative numbers? The clever fucks invented a new kind of number called an "imaginary number." :) Why not? Who do you think invented negaative numbers, the lawyers? No, the same guys who invented imaginary numbers.

Ok, sorry, got to run. So very quickly here's cutting to the chase:

i = squarre root of -1. Thus (i)squared = -1, which is as plain as day a... real number!

Hint: two imaginary numbers in the bush get you a real number. And that's the fuckin'genious behind imaginary numbers. Really, imaginary numbers are nothing more than placeholders. But brilliant invention nonetheless :)

Trivia: Half the numbers in the universe are imaginary numbers.

PS: The fancy-dandy phrase "complex numbers" just means a real number and an imaginary number together: example: 5 + 6i.

The topic of imaginary/complex numbers is introduced after algebra and before calculus: pre-calculus. If you don't want your kid to get lost or freak out over the topic, tell him or her to not look it up on sites like wikipedia.

Peter Pan said...

Electronics is chock full of mathematical models.

Peter Pan said...

Impedance is said to be a complex number, yet it is simply a two dimensional vector.
What's the big deal about vectors?

Matt Franko said...

“We’re out of vectors!” :p

AXEC / E.K-H said...

All one needs to know about economics and math in general and MMT and math in particular:

• economics is fake science,
• economists are too stupid for the elementary algebra of macrofoundations,
• Walrasianism, Keynesianism, Marxianism, Austrianism, MMT, Pluralism are mutually contradictory, axiomatically false, materially/formally inconsistent,
• economists/MMTers are clowns/useful idiots in the political Circus Maximus.

Morons on math
https://axecorg.blogspot.com/2017/06/morons-on-math.html

MMTers: too stupid for simple math
https://axecorg.blogspot.com/2020/02/mmters-too-stupid-for-simple-math.html

MMT: How mathematical incompetence helps the Kelton-Fraud
https://axecorg.blogspot.com/2018/07/mmt-how-mathematical-incompetence-helps.html

Cross-references Math/Mathiness
https://axecorg.blogspot.com/2015/05/mathiness-cross-references.html

Egmont Kakarot-Handtke