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All of Steven Joyce's Comments + Replies

What conclusions can be drawn from a single observation about wealth in tennis?
Steven Joyce62

Your math is wrong.

1e-30 is the probability that two randomly selected women are both billionaire-adjacent and top-10 tennis players, assuming no correlation between the two. To compare to the observed 20%, you need to instead calculate the probability that a woman is a billionaire, conditional on being a top-10 tennis player, assuming no correlation. Using the binomial formula, the probability of having exactly two billionaire women in the top 10 is about 4.5e-11. (The probability of having more than two billionaire women in the top ten is negligible rela... (read more)

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Mistakes people make when thinking about units
Steven Joyce54

"A million times a million is a billion" should be "A million times a million is a trillion"

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6RogerDearnaley
There was, at least in the UK a few decades ago, a definition were this was true, since a billion was 10^12 and a trillion was 10^24 and numbers like 'two thousand million billion' were meaningful (that's 2 * 10^39). The American definition where a billion is 10^9 and a trillion is 10^12 has long since taken over, however.
1Isaac King
Oh whoops, thank you.
Dath Ilan vs. Sid Meier's Alpha Centauri: Pareto Improvements
Steven Joyce250

There's a standard explanation in game theory as to why wars or fought (or lawsuits are brought to trial, etc.), even when everyone would be better off with a negotiated settlement that avoids expensive conflict. Even assuming that it's possible to enforce an agreement, there's still a problem. In order to induce militarily strong parties (in terms of capability or willingness to fight) to accept the agreement rather than fight, the agreement must be appropriately tilted in their favor. If there is asymmetric information about the relative military strength of the parties, then in equilibrium, wars must be fought with positive probability.

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9Ben
Perhaps not standard. But another possible explanation of why wars are fought is that any specific war might be a sub-optimal move, but that making a plausible pre-commitment to a war as a  general policy is a good disincentive for other people to avoid conflicts with you. You asked for some territory from me, we could negotiate a mutually acceptable compromise, but then maybe all those other jerks also start asking me for land. Maybe I value that disincentive highly.  Another factor is that all the farmers and mooks who will loose limbs and lives are not invited to the decision-making table. This maybe moves the goalposts, as we don't do game-theory for the countries, but for their leaders/negotiators. eg. "This war will make me a national hero. Plus this is good for our country as it exists as a concept, in that it gets physically bigger and more complete. My own place in history and the integrity of my country's identity are each worth roughly one of my own limbs to me. Fortunately I will only have to pay with other people's, so by my utility function this war is a steal!"
7Mark Xu
Isn't there an equilibrium where people assume other people's militaries are as strong as they can demonstrate, and people just fully disclose their military strength?
4Thomas Kwa
I guess the obvious question is how dath ilan avoids this with better equilibria-- perhaps every party has spies to prevent asymmetric information, and preventing spies is either impossible or an escalatory action met with retaliation?
Build Your Number Sense
Steven Joyce30

There's an error in your 1% of a billion dollars example.

You write one million dollars x 100, which is 10% of one billion dollars, not 1%

It would only take 9 more blocks like this to get back to the one billion dollars.

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2DirectedEvolution
Thanks, I was kind of hasty in throwing the visual examples together :D
Attach Receipts to Credit Card Transactions
Steven Joyce10

Something very close to this is done with fleet cards (cards given by long-haul trucking companies to their drivers to pay for gas and other expenses). At the high-end, these cards capture a great deal of data, comparable to a receipt. (Not exactly equivalent -- it's more detailed then a typical receipt for some data fields, but doesn't include everything that can be put on a receipt). It's expensive to implement and maintain these sorts of data capture systems, since a receipt is very flexible about the data it can contain. As a result, mor... (read more)

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2jefftk
I just tried reading some about fleet cards, and found this exxon faq and this sales page. It sounds like the number of gallons gets sent automatically, and you can set up the card to prompt for an odometer reading to be sent too. This is neat, though very fuel-specific. When you say "at the high-end, these cards capture a great deal of data, comparable to a receipt", what are you thinking of? Why do you say that? I would expect comparing what was being purchased to a model from this user's history and a model of fraudulent transactions would be very helpful!
An optimal stopping paradox
Steven Joyce50

TLDR: The paradox goes away if you make price endogenous, i.e., it only occurs because your assumption about the value growth over time that is inconsistent with the profit flows.

The paradox stems from the fact that you've made inconsistent assumptions: that the value of the company increases linearly over time, and that the company never generates a flow of profits (i.e., the only value comes from the sale). If profits are zero, the equilibrium price is constant at zero, and investors are indifferent between holding the company and selling it at any ... (read more)

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Can dying people "hold on" for something they are waiting for?
Steven Joyce190

Two studies that have found some evidence that the timing of death responds to incentives created by changes in estate taxes:

1. From the USA: Kopczuk and Slemrod (2003), https://pdfs.semanticscholar.org/afd2/7f878ba71c9ec28258407a1e9b34150cd9d0.pdf

2. From Sweden: Eliason and Ohlsson (2013), http://www.diva-portal.org/smash/get/diva2%3A457378/FULLTEXT01.pdf.

These are far from definitive, but are definitely suggestive.

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