## Posts

Comment by wangscarpet on Covid 6/10: Somebody Else’s Problem · 2021-06-12T17:05:28.504Z · LW · GW

Can you extrapolate the infectiousness ratio between the newest most virulent strain and the original? I assume the original has all but died out, but maybe by chaining together estimates of intermediate strains?

Comment by wangscarpet on Book Review of 5 Applied Bayesian Statistics Books · 2021-05-23T18:31:49.325Z · LW · GW

I'm reading BDA3 right now, and I'm on chapter 6. You described it well. It takes a lot of thinking to get through, but is very comprehensive. I like how it's explicitly not just a theory textbook. They demonstrate each major point by describing a real-world problem (measuring cancer rates across populations, comparing test-prep effectiveness), and attacking it with multiple models (usually frequentist to show limitations and then their Bayesian model more thoroughly. It has a focus on learning the tools well enough to apply them to real-world problems.

I plan to start skimming soon. It seems the first two sections are pedagogical, and the remainder covers techniques which I would like to know about but don't need in detail.

Edit: One example I really enjoyed, and which felt very relevant to today, was on estimating lung-cancer hotspots in America. It broke the country down by county, and first displayed a map of the USA with counties in the top 10% of lung-cancer rates. Much of the highlighted region was in the rural southwest and Rocky mountain region. It asked, what do you think makes these regions have such high rates? It then showed another map, this one of counties in the bottom 10% of lung-cancer rates, and the map focused on the same regions!

Turns out, this was mostly the result of these regions containing many low-population counties, which meant rare-event sampling could skew high very easily, just by chance. If the base rate is 5 per 10,000, and you have 2 cases in a county with 1,000 people, you look like a superfund site. But sample the next year and you might find 0 cases: a county full of young health-freaks.

If you model lung-cancer rates as a hierarchical model with a distribution for county cancer-rates, and each county as being sampled from this, and then sampling cancer events from it's specific rate, then you can get a Bayes-adjusted incidence rate for each county which will regress small counties to the mean.

This made me read Covid charts which showed hot-spot counties much differently. I noticed that the counties they list are frequently small. Right now, all the counties on the NYTimes list, for example have less than 20,000 people in them, which is, I believe, in the bottom 25% of counties by size roughly.

Comment by wangscarpet on Iterated Trust Kickstarters · 2021-04-22T16:00:34.469Z · LW · GW

I think it comes from a feeling that proportion of blame needs to add to one, and by apologizing first you're putting more of the blame on your actions. You often can't say "I apologize for the 25% of this mess I'm responsible for."

I think the general mindset of apportioning blame (as well as looking for a single blame-target) is a dangerous one. There's a whole world of things that contribute to every conflict outside of the two people having it.

Comment by wangscarpet on Ranked Choice Voting is Arbitrarily Bad · 2021-04-05T14:34:38.912Z · LW · GW

I also think that the example isn't perfect (although I haven't formalized why yet). But, you're describing tactical voting, which is considered one of the "downsides" of RCV.

Comment by wangscarpet on Why do stocks go up? · 2021-01-18T18:34:20.904Z · LW · GW

I think things become simpler when you look at the sum of all stocks, versus particular ones. Then, you only need to consider the market cap of the entire stock market, and what makes it change over time.

The economy is much bigger than the stock market. Money flows from small companies to larger one as the economy consolidates -- since the former are more likely to be publicly traded than the latter, that makes the market become bigger.

It's easier to invest in the stock market now than in the past. Since it's accessible to more people, then more people's money can be put in it. So, the market cap goes up.

Finally, as inequality increases, more of a fraction of wealth is disposable, and therefore can be invested. That makes the market grow as well.

I'm sure there are many other reasons along these lines.

Comment by wangscarpet on Luna Lovegood and the Chamber of Secrets - Part 11 · 2020-12-28T16:57:11.697Z · LW · GW

When reading HPMOR, I thought Harry's decision to not kill Voldemort was hubris, even considering his morals. He should have known that all plans have a non-zero chance of failing, and that Voldemort coming back could be an existential risk. So, finite harm now to stop a small chance at nearly infinite harm later. Nice to see this coming to bite him. I'm looking forward to the conclusion!

Comment by wangscarpet on Covid 12/17: The First Dose · 2020-12-18T15:53:00.054Z · LW · GW

In what world is giving the second dose to the same person, raising them from 87% to 96% protected, a higher priority than vaccinating a second person?

One benefit of 96 vs 87 is that the former could allow you to live an un-quarantined life, while the latter wouldn't result in much behavioral change. Clearly, the one-dose is better for net deaths etc, but the QALY calculation looks a little different.

I still agree with you. But it's worth considering the above reasoning for completeness.

Comment by wangscarpet on Impostor Syndrome as skill/dominance mismatch · 2020-11-05T23:08:13.618Z · LW · GW

So interesting that I thought you were going to go the opposite direction at the end. I have felt slight amounts of imposter syndrome before, and it came from feeling like a well-liked and well-respected person whose skills did not fully back up my reputation. So, I was high on the social hierarchy but I perceived it coming from dominance and not prestige.

Comment by wangscarpet on Limits of Current US Prediction Markets (PredictIt Case Study) · 2020-07-15T14:47:14.397Z · LW · GW

A parallel problem with prediction markets: at non-financial-industry scales: they're used as signals of confidence. How often do you see, after someone makes a bold claim, a response saying to "put your money where your mouth is." But just the act of signalling confidence can be intrinsically valuable to the person making a claim. In bet-capped places like predictit, this can make equilibrium that are different from optimal, because there are non-monetary incentives at work.

Comment by wangscarpet on Learning the prior · 2020-07-07T01:15:57.518Z · LW · GW

This is a good and valid question -- I agree, it isn't fair to say generalization comes entirely from human beliefs.

An illustrative example: suppose we're talking about deep learning, so our predicting model is a neural network. We haven't specified the architecture of the model yet. We choose two architectures, and train both of them from our subsampled human-labeled D* items. Almost surely, these two models won't give exactly the same outputs on every input, even in expectation. So where did this variability come from? Some sort of bias from the model architecture!