Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

How I'm Predicting Baseball Outcomes

blog.zachschnell.com

Post reply on HN
Print view View original

31–40 of 45 posts

Re: How I'm Predicting Baseball Outcomes

#31

Post by jaredmck »

iross wrote: post #10
iguana wrote: post #5

Isn't this an example of the gambler's fallacy, that previous outcomes impact future outcomes?

If I remember correctly, the gambler's fallacy is for fully independent events. I think the assumption here is that the team's performance in a game will impact their next result. After a win, they get on a roll. After a loss, the coach gives them a stern talking to and they come out playing a bit harder the next night. There's some correlation between games, but I'd say it's mostly independent... I'm not a statistic…

Playing hard has very little to do with winning in baseball - oh, I didn't try hard so I didn't hit the ball? Or didn't take a walk? Or didn't watch the ball and it hit me in the head?

I pitched 5 mph less due to mental effort? Well, now you don't get to throw again for 5 days. Or you walked 15 batters in a row to try and get taken out of the game. It's not going to make your night easier, you sit there till the game is finally over. No clock to run out. Just outs.

Re: How I'm Predicting Baseball Outcomes

#34

Post by jinfiesto »

gfunk911 wrote: post #24
icelancer wrote: post #21

As someone who has written 10k+ loc on simulators, markov chaining, and done tons of analysis on baseball projections... I don't know where to start. I honestly don't. (You are very, very far off the correct methodology.) But maybe this is a good place, I guess. http://www.oakton.edu/user/4/pboisver/AABaseballMath.html I am not trying to be a jerk. But ask yourself: If it were that trivial, why wouldn't it be a snap…

Agreed. The post isn't clear at all what his goal is, and the methodology makes no sense

Yeah. My first thoughts were that the methodology is extremely questionable. I know it's arguable that successive games aren't necessarily independent trials, but analyzing a game in terms of streaks, is so incredibly "un-mathematical" I don't know where to start. To top it off, there's no reasoning about why it might be the case that "streak" analysis might give insight into the why of things.

Re: How I'm Predicting Baseball Outcomes

#35

Post by the_cat_kittles »

icelancer wrote: post #21

As someone who has written 10k+ loc on simulators, markov chaining, and done tons of analysis on baseball projections... I don't know where to start. I honestly don't. (You are very, very far off the correct methodology.) But maybe this is a good place, I guess. http://www.oakton.edu/user/4/pboisver/AABaseballMath.html I am not trying to be a jerk. But ask yourself: If it were that trivial, why wouldn't it be a snap…

Thank you- I also built several baseball sims and this article is just insultingly ignorant! Maybe thats a little extreme, but that was my reaction.

Re: How I'm Predicting Baseball Outcomes

#36

Post by the_cat_kittles »

localhost3000 wrote: post #19

google tangotiger and then read his book. baseball prediction has been done to death by the sabermetrics community but this guy is one of the absolute best.

tango is awesome, but saying he is the best is misleading. He is just one point of view, albeit a fairly wise and proven one. There are many other people with other opinions, using other techniques, and they have gotten good results- He is a bit of a curmudgeon when it comes to modern statistical techniques and machine learning.

edit: sorry, misread "one of the" as "the"...

Re: How I'm Predicting Baseball Outcomes

#37

Post by jaredmck »

zsch wrote: post #17
jerf wrote: post #16

Earlier quoted context omitted.

Are they? jerf@jerfhom:~$ python Python 2.7.3 (default, Sep 26 2012, 21:51:14) [GCC 4.7.2] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> import random >>> 94.0/(94+68) 0.5802469135802469 >>> winp = 94.0/(94+68) >>> games = [] >>> for x in range(50): ... games.append('w' if random.random() >> ''.join(games) 'wLwLwwwwwLwLwLwwwLLLwLwwLwLLLwwLwwwwwLwwwLwwLLwLLw' In my full simulatio…

The 2012 data I used as the basis of my program actually had the same thing you describe – the longest streak was an 8 game losing streak despite having more wins than losses overall. And I understand exactly where you're coming from. This is very preliminary, and if anything it was good coding practice for me. Though I very much intend to incorporate more significant factors like the lineup, the opposing team, and t…

First improvement: do this for every team ever. Then combine for all teams, first in an individual season, then try basing the win% iteratively based on more history.

Based on these models, you should have some good examples of selection bias, and see how the model changes based on what you are not testing for, but what is implicit in the data (since data is merely a set of samples of data generated by one iteration of the (unknowable to some degree) true talent functions for each team (player, lineup decision, injury, close call by an ump, etc.)

If you're interested in going down the rabbit hole, there's tons of people who can show the way (and they're nice! At least tangotiger is way nicer than he should be in listening to people who have put no effort in understanding what is good and what is beginner's blind bliss)

Hot and cold streaks are just random variance, so is whether balls are hit within reach of fielders or safely out of reach, given a certain contact quality (ground ball, fly ball, infield pop up, or line drive all have vastly different tendencies to fall for a hit - line drives ~.600-700 babip if I recall, FB ~ low .200ish, GB ~ .300, pop up 0ish?) point is these are all known, to se degree, given the historical data.

If anyone wants to explore this stuff further let me know & I can point you to the right spots to help a specific interest?

Re: How I'm Predicting Baseball Outcomes

#38

Post by glitch273 »

icelancer wrote: post #21

As someone who has written 10k+ loc on simulators, markov chaining, and done tons of analysis on baseball projections... I don't know where to start. I honestly don't. (You are very, very far off the correct methodology.) But maybe this is a good place, I guess. http://www.oakton.edu/user/4/pboisver/AABaseballMath.html I am not trying to be a jerk. But ask yourself: If it were that trivial, why wouldn't it be a snap…

Yup, and his analysis does not take the strength of the team into account (Vegas calls this the spread). It like betting the Miami Heat with Lebron will win a high percentage of games, well of course, everyone can make that bet.

Re: How I'm Predicting Baseball Outcomes

#39

Post by thret »

icelancer wrote: post #21

As someone who has written 10k+ loc on simulators, markov chaining, and done tons of analysis on baseball projections... I don't know where to start. I honestly don't. (You are very, very far off the correct methodology.) But maybe this is a good place, I guess. http://www.oakton.edu/user/4/pboisver/AABaseballMath.html I am not trying to be a jerk. But ask yourself: If it were that trivial, why wouldn't it be a snap…

http://espn.go.com/blog/playbook/dollars/post/_/id/2935/meet...

Just a random article. I've met him through poker. He had a radio show for a while, and he stated that if you have a 2% edge over a bookie, you can easily make a million dollars a year. Anyone who thinks they have an edge and isn't also very wealthy is simply mistaken.

Re: How I'm Predicting Baseball Outcomes

#40

Post by icelancer »

thret wrote: post #39
icelancer wrote: post #21

As someone who has written 10k+ loc on simulators, markov chaining, and done tons of analysis on baseball projections... I don't know where to start. I honestly don't. (You are very, very far off the correct methodology.) But maybe this is a good place, I guess. http://www.oakton.edu/user/4/pboisver/AABaseballMath.html I am not trying to be a jerk. But ask yourself: If it were that trivial, why wouldn't it be a snap…

http://espn.go.com/blog/playbook/dollars/post/_/id/2935/meet... Just a random article. I've met him through poker. He had a radio show for a while, and he stated that if you have a 2% edge over a bookie, you can easily make a million dollars a year. Anyone who thinks they have an edge and isn't also very wealthy is simply mistaken.

2% is enormous and can't last for very long, of course.
Post reply on HN