Showing 105 to 108

History of statistics

See Eugenics

History of Bayesian methods

Reverend Thomas Bayes was inspired by David Hume's idea that you can only base knowledge on experience. In 1763 (posthumously) his paper was published explaining the basic theorem of how to update a preexisting guess based on evidence.

Pierre-Simon Laplace picked it up, and nine years later (in 1774) he presented the fundamental principles of Bayesian probability theory. He tested it by working extensively on demography. Seven years later (in 1781) he gave Bayes' Theorem its current form. Some say Bayesian statistics may be more rightly called Laplacian statistics.

After Laplace, the concept of probability as a measure of personal uncertainty fell out of favor for a century (why?). Karl Pearson and Francis Ysidro Edgeworth revisited it for a bit, but these names are largely associated with frequentism.

Bruno de Finetti (1906–1985) dedicated his life to the idea of subjective probability. He began his book on probability theory with the declaration: "PROBABILITY DOES NOT EXIST". A famous paper in 1930 and another in 1974 – in the latter, he wrote: My thesis, paradoxically, and a little provocatively, but nonetheless genuinely, is simply this: Probability does not exist. The abandonment of superstitious beliefs about the existence of the Phlogiston, the Cosmic Ether, Absolute Space and Time, … or Fairies and Witches was an essential step along the road to scientific thinking. Probability, too, if regarded as something endowed with some kind of objective existence, is no less a misleading misconception, an illusory attempt to exteriorize or materialize our true probabilistic beliefs.

Independently from Bruno de Finetti, Frank Ramsey arrived to the same conclusions (1931). Harold Jeffrey focused on "objective probability" while maintaining a Bayesian framework (1939).

Many applied Bayesian methods were developed during the Second World War, notably by Alan Turing. Also, Stanislaw Ulam discovered Monte Carlo simulation whereupon John von Neumann programmed the ENIAC (the first computer!) to do it.

After the Second World War, we saw a so-called neo-Bayesianism, a revival that emphasized decision theory. That's to say it developed the use of probability theory to guide your reasoning about life in general. Today it underlies the normative prescription of rational behavior from which irrational people depart: psychologists and cognitive scientists measure irrationality as departures from Bayesian reasoning. A big figure here is Leonard Savage, who synthesized the work of Bruno de Finetti and Frank Ramsey in 1954.

Dennis Lindley was visiting the university in Chicago where Leonard Savage worked and got inspired by meeting him. In a 1957 paper, he discussed how the frequentist ("conventional") approach and the Bayesian approach can disagree regarding hypothesis testing, something now called Lindley's paradox – not really a paradox.

In his 2006 book, Understanding Uncertainty, he wrote Uncertainty is a personal matter; it is not the uncertainty but your uncertainty.

Since Bayesian methods were calculation-heavy and impractical, they were rarely used (though John Tukey proposed Bayesian methodology to predict the 1962 US elections) up untitl the 90s.

From the 90s on, we have had two things going for us: powerful computers as well as relatively efficient algorithms like Markov chain Monte Carlo (MCMC). Now it is finally possible for all researchers to use Bayesian modeling.

What links here

Created (3 years ago)

Topic notes

#org-roam

Jethro Kuan said he started out writing a lot of "definition notes" which felt Wikipediaish. Then he found that writing "claim notes" instead, where the title is a proposition or so, feels more natural and leads to more creativity.

You can still have definition notes, particularly if they are "topic notes", indexes over a topic.

My problem: I already have some well-taxonomised PKM things.

  • How do I avoid destroying the information in the taxonomy as I convert it to Roam?
  • How do I keep it just as easy to browse a category/tag as it was to simply expand a subtree in my stats.org?
    • Such a subtree also embedded other info:
      • the ordering of items could matter
      • Though a flat hierarchy, it was sometimes grouped e.g. in my copia.org I had a series of "Meta: …" headlines for reminding myself about how to write other copia headlines and their bodies

What links here

Created (3 years ago)

PARA

(fortelabs.co/blog/para/)

Projects, areas, resources, archive.

If you squint, it's a simplification of GTD that stays under the magic number 4. Whenever you think of how to classify a thing, you just need this 4-word sentence.

They come in order of actionability.

Must take care to keep a crisp difference between Projects and Areas [of responsibility]. Hash out any confusion, look it up online if need be.

Projects:

  • Have a deadline

Areas:

  • A standard to be maintained
  • Don't have a deadline

An exercise is to make your projects list and goals list, then see which projects you can connect to a goal.

  • Projects without goals are hobbies.
  • Goals without projects are dreams.

You should be able to see all your projects at once.

It doesn’t make sense to have to drill down through a bunch of non-actionable information in order to find the actionable stuff.

[…]The second reason is visual clutter. Using areas as the top level of the hierarchy means that, even if I collapsed all the stacks, I would still be faced with 22 notebooks.

As for areas v. resources:

The key here is to keep in mind that areas are Areas of Responsibility. There is a very clear line between things that you are responsible for, and those that you’re merely interested in.

Areas of Responsibility are the roles you take on in life and the hats you wear (Spouse, Mother/Father, Team Leader, Soccer Coach), the ongoing standards where the buck stops with you (Product Development, Company Newsletter, Legal), and things that take a certain amount of constant attention (Exercise, Finances, Apartment, Pets).

Resources are interests (web design, crowdfunding, woodworking, frisbee golf, bio-hacking), themes (psychology, politics, leadership, integrity), and assets (stock photos, typography links, marketing swipe file, product testimonials, code snippets). I even use lower-case titles with resource notebooks, to remind myself that they are just interests, […]

There is another useful guideline here: put personally relevant information in Areas, and generally useful information in Resources. For example, in my Health (area) notebook, I’ll have blood panels, notes from doctor’s visits, medical bills, and vaccination records (all things relevant only to me personally), whereas in my workouts (resource) notebook, I’ll have exercise research, interesting articles on alternative workouts, and recommended training regimens. This gives me the confidence to share any note in a Resource notebook (or even entire notebooks) on the fly, without having to first comb through it for any personal information. And I can connect the two categories by inserting links in Area notes pointing to Resource notes

It's natural for things to move between all of the four categories – a project to become an area, a resource to become a project etc. For descriptive examples, see manual.

You may be wondering, “WHEN exactly am I supposed to be performing all this work ‘flowing’ information from one notebook to another?” The subtext being: “WHO in the world has time for such fastidious, detailed record-keeping?!”

You could schedule these “re-orgs” on a strict timeline, performing them at set intervals like daily, weekly, and monthly. But I don’t recommend it. I would suggest performing organizational work opportunistically, as opportunities arise, instead of pedantically, or “just because.” I call this approach Just-In-Time Organization. What this looks like is making changes to your organizational structure in small batches, as you go along and happen to notice incremental improvements, not in big batches as part of a dedicated effort.

For all the flows I describe above, don’t worry about flowing notes from one category into another with perfect precision. There is no “done,” thus you don’t have to worry about what “done” looks like! You always have search as a backup tool to find whatever you’ve missed or misplaced.

Some people ask why I break out my Areas of Responsibility into such small buckets. In my case, 22 of them:

This is really a personal decision, but for me it holds a valuable benefit: it makes it easier for me to determine whether or not I’m meeting my personal standard in a given area. If I had only “Work” and “Personal,” it would be difficult for me to identify where I was falling short and what changes I should make. But having my life broken out into 22 areas allows me to evaluate them more objectively.

What links here

  • 2024-03-27
Created (3 years ago)

Venus

Adjective: Venerian or Venusian.

Length of a day

Look at these numbers:

  • Orbital period (Venus year): 224.7 Earth days
  • Rotation period (Venus day): -243 Earth days (retrograde)

A Venus day (the time its globe takes to rotate 360 degrees around its own axis) is longer than a Venus year (the time it takes to travel a loop the Sun)!

That's pretty damn slow, compared to Earth which manages to spin 365 revolutions before completing one orbit.

But how slowly does the Sun move across the Venus sky? That's usually what we mean when we talk about a "day".

Because of the retrograde rotation, a solar day on Venus (the time from one sunrise to the next sunrise) takes "only" 116.75 Earth days.

I wonder, if the planet's rotation was prograde like most planets, would a solar day be horribly long?

Yes. Normally, if you imagine a non-rotating body orbiting the Sun, it would see the Sun moving across its sky, but a slow prograde rotation cancels out much of that, seemingly slowing down the Sun's path across the sky. So how long would it take from one sunrise to the next?

The difference between its day and its year is about 20 Earth-days, so on every completed orbit, the planet's rotation would only have progressed 20 days, or about a twelfth, of the full 243 days. During the orbit, it was mostly "rotating along" like a tidally locked satellite. In short, if Venus rotation had been prograde, a solar day would take more than 2500 Earth days, or seven years between sunrises!

Colonization

Venus is one of the best colonization sites in our solar system.

  • While it has temperatures around 500 C on the ground, you can find more Earth-like conditions at an altitude of 55,000 m above the ground: livable temperature and pressure. These beat Mars.
    • The Venerian atmosphere is crazy-thick, so even at the 50 km altitude, there's still enough above to protect against solar radiation and meteorites. This beats Mars.
    • The atmosphere can be used to manufacture oxygen more easily than on Mars.
  • After we realize that Earth air acts as a lifting gas on Venus, it's clear that you could build cities that float in the air on Venus, same as when you let go of a helium balloon on Earth and watch it float up into the sky. Isn't that great?!
    • And the cities wouldn't need big balloons above, the way airships on Earth are made of a big balloon and only a small gondola underneath where people board. Because we can breathe that air, we can occupy the balloon itself, so to speak (rather, there'd be no balloon, just a very big gondola). That gives you plenty of space to walk around.
  • While these cities need be airproof, it won't spell doom if it springs a leak somewhere. The pressure inside the city is the same as the Venus atmosphere outside, so Venerian air would come in at normal gas-mixing rates, affording many hours for engineers to patch the leak.
  • In theory, you can even step outside on the balcony without a spacesuit and crack open a beer – all you need is a breathing apparatus in your nostrils. But stay inside when it rains; the rain is sulfuric acid strong enough to dissolve most matter.
    • Not sure if you'd ever dare expose your mouth. You know, when we hold our breath for too long, what induces us into a panic is not the absence of oxygen (the lungs consume oxygen very slowly, actually) but the rising amounts of carbon dioxide. IIRC, less than a percent CO2 is enough to cause us to hyperventilate and behave like we're drowning. On Venus, the air is closer to 100% CO2; what would it feel like to accidentally suck in some of that through your mouth? I guess you'd lose all control of your body and die shortly thereafter.
  • A major drawback is the lack of local raw materials – you'd have to send drones to the ground to gather stuff, and all drones sent by the USA and the Soviet Union in the 20th century broke in less than 2 hours under the intense heat and pressure.
    • Reycling would be a big deal.

Related

Created (3 years ago)
Showing 105 to 108