Thursday, October 28, 2010


I'm supposed to tutor for a introductory macroeconomics class, but I haven't had time until today to look at what they're learning. I opened the first set of slides and saw this statement:

Unemployment is bad for the individual unemployed workers, because they can't make a living.
That seems obvious. But I think it misses the real problem with unemployment.

Unemployed workers can collect unemployment, at least in the short run. But that doesn't stop unemployed people from being unhappy. The reason unemployment is so bad is because of the psychological effects:

1a. Being laid off or fired hurt your self-esteem
1b. It makes you worry about being able to do jobs in the future
2. It cuts you off from your friends

These psychological effects are what cause so many unemployed people to become depressed, which has a negative impact on their families. That is the real toll of unemployment.

On the bright side, it's probably easier to teach people to cope with being laid off and to integrate people into social circle outside their workplace than it is to eliminate the search frictions (etc.) that cause unemployment.

Don't take this seriously

They say Asian people are, on average, the most prejudiced racial group in the U.S. They tend to look down on blacks in particular and prefer to keep company almost solely with other Asians.

The question is: do Asians hate blacks more than they love other Asians?

(If you don't know, Tiger's mom is Asian and his dad is black.)

It looks like they hate blacks more. The fact that Tiger is black dominates for 58.9% of Asians. And as we might have guessed, despite the fact that Asians are far less likely to follow sports, they are more likely to have an opinion on Tiger Wood than whites or blacks.

Sunday, October 24, 2010

Bayesian Approach

The NFL blew a call today because they don't appreciate the Bayesian philosophy in statistics.

Here's the situation. A player for the Steelers was running to the end zone. He lost the ball before he scored a touchdown, but the referee didn't see and ruled it a touchdown. The Dolphins challenged the the officials ruled that it was indeed a fumble but that they couldn't give the ball to the Dolphins because the Steelers always get preference (see Super Bowls XL and XLIII), er . . . . because it wasn't clear who recovered the ball.

Let's suppose that the league wasn't just favoring the Steelers and that they believe that when there is a loose ball and the refs can't determine who recovered, the ball should go the offense. Under that rule the ball will go the right team approximately 50% of the time, since the offense will recover a loose ball about half the time. Under a rule that gives the ball to the team that appears to have recovered the ball--the team that is most likely to have recovered the ball--the ball will go to the team that recovered the ball > 50%.

The later rule is based on the Bayesian philosophy, which is the dominant point of view in statistics today. Other approaches have fallen in disfavored because they give an (often) arbitrary preference to some hypothesis--in this case that the Steelers recovered.

The moral of the story is that everyone should study statistics, or just use common sense. But a lot of people lack the later . . .

Saturday, October 16, 2010

Does the MLB need longer playoff series?

For most of the 20th century only two teams made the playoffs in baseball: the NL pennant winner and the AL pennant winner. There were only one playoff series--the World Series. In 1969 that changed to four teams--one from each division (East and West) of each league. In 1995 it changed again to include eight teams--three division winners and two wildcards.

The changes have made baseball more exciting. Every year there are a lot of teams in the hunt for a wild card or division spot. In the 1920s and 1930s the Yankees often wrapped up the AL pennant by early September and baseball was dull until the Fall Classic. Not anymore. I wouldn't do away with the wildcard or combine divisions.

But one thing did bother me. The first round of the MLB playoff is a short best of five series. And baseball teams have more parity than most sports clubs. For any given game even a bad team has a good chance of beating a good team. A worse team is less likely to win a best of 3 series than just a single game, and even less a best of 5. In general the longer the series the more likely the better team will win the series. My suspicion is that because the first round of the MLB playoff is so short there is an unreasonable large chance that the worst team will win in the first round.

You could make a case that's how it should be. Sports are about chance. They're about showing up and performing well on a specific day, not being the best on average. But, on the other hand, most people feel a sense that the rules should be designed so that "the best man (team) wins."

I decided to explore numerically how much of a difference it makes that the first round is a 5 game series as opposed to 7, 9, or 11. Longer series are better because give fans more games to watch and the better team is more likely to win, but they have a cost in sucking some of the drama out of the playoffs. I wanted to quantify the gain from the better team being more likely to win.

Call the probability that the better team, say the Rays, will win p. Then you can model the Rays chance of winning with a mathematical construct called the Binomial Distribution. I used that model in Excel to simulate the Rays chances of winning for p = 0.42, 0.44, ..., 0.60 for a 5, 7, 9, and 11 game series. To my surprising the length of the series doesn't make much of a difference for teams that are relatively equal (which is true for playoff teams). The graph below shows the effect of lengthening the series.**

I'd still like to see longer series. 9 for the first round and 11 for later rounds. But at the same time I can see why one can't complain too much. In football the playoff "series" are just one game rounds and we think that amount of chance is acceptable--even exciting.

But I'm still bitter than the Rays got bumped by a vastly inferior team.

* - This averages out pitcher effects. What I mean is that the Phillies might have one great pitcher that makes winning Game 1 likely, but the average of their likelihood of winning Games 1, 2 and 3 is probably < 60% against another playoff team.

** - This model leaves out the effect on pitching rotation choice. If the playoffs could potentially go 29 games a manager that might use a 3-man rotation under the current system might switch to a 4 or 5 man rotation. That effect could be large in some cases (e.g. 2001 Diamondbacks).

Friday, October 8, 2010

The Caped Crusader

To follow up on the last post. Batman 3 comes out in less than 2 years. Here's my hope and guess for some elements of the plot.

First, the title will and should be The Caped Crusader. It gels nicely with the other two and captures the third-act aspect of the film. This movie is going to have a happy ending, it should have a title that captures the good side of the batman.

Second, the villians will be the Riddler and the Black Mask. The movie will deal in part will Bruce's inner turmoil post-Rachel's death and with the city hating him. He won't have a love interest because he'll come into his own as the Caped Crusader and embrace his future fighting crime in the city. (He could also die, but I don't think so.)

The movie will start with crime getting worse because Batman is hampered by Gordon's men's hunt for him. This will leave an opening for the Black Mask to assert himself in the crime world and fill the power vaccum left by the deaths of the three bosses in The Dark Knight. Meanwhile, the police will hire Edward Nigma to help them hunt down Batman and find out his identity. The Black Mask's backstory will come out alongside his history with Bruce and he'll probably kidnap Lucious or something at some point. I don't know how they'll work in the over-the-top action or keep the thrilling pace of TDK up--and I don't expect them to quite match it.

But the end should be a little more emotional and a little more satisfying because it should be conclusive. I hope they trim this one to under 2:15 too.


The rumor mill says Batman 3 (The Caped Crusader?) will feature Killer Croc as the primary villan and part of the movie will be set outside of Gotham with shooting in New Orleans.

Doubt it. Nolan wouldn't touch a character like Killer Croc. I take this as evidence pointing toward the Black Mask. He was introduced when Millar was 15, so he fits the description too. I don't think they would set a major action sequence outside of Gotham either, so I suspect the New Orleans shoot, if it's real, is for a part like the Hong Kong part of The Dark Knight. The Black Mask makes a lot of sense because someone has to fill the void left by the deaths of Gambol, the Chechen and Maroni.

So right now I'm hoping for the Riddler and the Black Mask, and I think that combination is most likely. Not sure who I'd have play them. DiCaprio could work as the Black Mask, but I'd like to see them find a no-name who fits better.

Wednesday, October 6, 2010

Bad Argument Technique #3

To continue my series on how to make a bad argument I'm going to introduce a third technique. This one is mainly useful in discussion about ethics, law, or politics. You can use it to lose an argument ASAP whenever what is fair or right is at issue.

The basic strategy is this. You presume that you or something about you is special and deserves special consideration, but that doesn't apply to anyone else. For instance, suppose you're talking about some cultural practice. You think that it's fine other people have their traditions or practices--maybe they only pass things with their left hand, or they always go to church on Sunday's, or they only eat Kosher food. You're fine with that, but you don't think they should impose those rules on others, like you. You feel its ok to use your right hand, not go to church, or eat non-Kosher food.

But you also have some cultural quirks. Say you don't think salt should be handed to people, just placed beside them. Or you think certain words are "bad" and shouldn't be said. Or you think it's gross if people chew tobacco (important caveat: chewing tobacco doesn't harm other people, just the chewer). You don't like those quirks and tell people and expect that that is a good enough reason for them to stop: you expect them to stop. Why? Because you asked. But when others asked you, you didn't think you were obliged to stop.

The normal rules (whether that others' cultural traditions should or should not be followed) don't apply to you because YOU are special. Everyone you're talking to, though, will rightly think you're a hypocrite.

Here is another example I stumbled on. My school (MIT) has a program to send people to countries for vacation during the summer and winter break and pairs that vacation with an internship. You can't get any money to go on a vacation unless you do an internship in the country. I pointed out that that's kind of dumb--why don't they just lottery $3,000 gift cards students could use to go on vacation or travel that weren't conditioned on where you did an internship. Instead of getting $3,000 to work for Google in China you could work for Google in California and use the $3,000 to travel to China in your break. I point out though, that because people tend to be risk averse, taking money from everyone to give them a lottery ticket for a bigger sum makes them worse off. Instead of paying $300 for a 1/10th chance at a $3,000 gift certificate you'd rather just have the $300. But someone responded that they liked both systems because they know in both cases they'd get a ticket (in other words, knowing ex post that they get a bunch of free money, they like it). Of course, no one else found that to be a compelling argument--why would what's fair depend so crucially on YOU unless you're special?