John C. Baez's Blog, page 84

Science, Models and Machine Learning

guest post by David Tweed

The members of the Azimuth Project have been working on both predicting and understanding the El Niño phenomenon, along with writing expository articles. So far we’ve mostly talked about the physics and data of the El Niño, along with looking at one method of actually trying to predict El Niño events. Since there’s going to more data exploration using methods more typical of machine learning, it’s a good time to briefly describe the mindset and highlight some of diffe...

The Stochastic Resonance Program (Part 2)

guest post by David Tanzer

Last time we introduced the concept of stochastic resonance. Briefly, it’s a way that noise can amplify a signal, by giving an extra nudge that helps a system receiving that signal make the jump from one state to another. Today we’ll describe a program that demonstrates this concept. But first, check it out:

• Stochastic resonance.

No installation required! It runs as a web page which allows you to set the parameters of the model and observe the resulting output signal...

Information Aversion

Why do ostriches stick their heads under the sand when they’re scared?

They don’t. So why do people say they do? A Roman named Pliny the Elder might be partially to blame. He wrote that ostriches “imagine, when they have thrust their head and neck into a bush, that the whole of their body is concealed.”

That would be silly—birds aren’t that dumb. But people will actually pay to avoid learning unpleasant facts. It seems irrational to avoid information that could be useful. But people do it. It...

El Niño Project (Part 7)

So, we’ve seen that Ludescher et al have a way to predict El Niños. But there’s something a bit funny: their definition of El Niño is not the standard one!

Precisely defining a complicated climate phenomenon like El Niño is a tricky business. Lots of different things tend to happen when an El Niño occurs. In 1997-1998, we saw these:

But what if just some of these things happen? Do we still have an El Niño or not? Is there a right answer to this question, or is it partially a matter of taste?

A r...

El Nino Project (Part 7)

So, we’ve seen that Ludescher et al have a way to predict El Niños. But there’s something a bit funny: their definition of El Niño is not the standard one!

Precisely defining a complicated climate phenomenon like El Niño is a tricky business. Lots of different things tend to happen when an El Niño occurs. In 1997-1998, we saw these:

But what if just some of these things happen? Do we still have an El Niño or not? Is there a right answer to this question, or is it partially a matter of taste?

A r...

Exploring Climate Data (Part 1)

joint with Dara O Shayda

Emboldened by our experiments in El Niño analysis and prediction, people in the Azimuth Code Project have been starting to analyze weather and climate data. A lot of this work is exploratory, with no big conclusions. But it’s still interesting! So, let’s try some blog articles where we present this work.

This one will be about the air pressure on the island of Tahiti and in a city called Darwin in Australia: how they’re correlated, and how each one varies. This article...

El Niño Project (Part 6)

guest post by Steven Wenner

Hi, I’m Steve Wenner.

I’m an industrial statistician with over 40 years of experience in a wide range applications (quality, reliability, product development, consumer research, biostatistics); but, somehow, time series only rarely crossed my path. Currently I’m working for a large consumer products company.

My undergraduate degree is in physics, and I also have a master’s in pure math. I never could reconcile how physicists used math (explain that Dirac delta functi...

The Harmonograph

Anita Chowdry is an artist based in London. While many are exploring electronic media and computers, she’s going in the opposite direction, exploring craftsmanship and the hands-on manipulation of matter. I find this exciting, perhaps because I spend most of my days working on my laptop, becoming starved for richer sensations. She writes:

Today, saturated as we are with the ephemeral intangibility of virtual objects and digital functions, there is a resurgence of interest in the ingenious mech...

El Niño Project (Part 5)

And now for some comic relief.

Last time I explained how to download some weather data and start analyzing it, using programs written by Graham Jones. When you read that, did you think “Wow, that’s easy!” Or did you think “Huh? Run programs in R? How am I supposed to do that?”

If you’re in the latter group, you’re like me. But I managed to do it. And this is the tale of how. It’s a blow-by-blow account of my first steps, my blunders, my fears.

I hope that if you’re intimidated by programming, m...

El Niño Project (Part 4)

As the first big step in our El Niño prediction project, Graham Jones replicated the paper by Ludescher et al that I explained last time. Let’s see how this works!

Graham did it using R, a programming language that’s good for statistics. If you prefer another language, go ahead and write software for that… and let us know! We can add it to our repository.

Today I’ll explain this stuff to people who know their way around computers. But I’m not one of those people! So, next time I’ll explain the...