THE BOOK--Playing The Percentages In Baseball

Tuesday, August 14, 2007

A fascinating study, worthy of some discussion I think…

Here is the Study

There is a discussion of said article, where I made some comments, on BTF.

Tuesday, July 31, 2007

And in these corners…

It’s the amateur statisticians-bettors / professional sports fans
v
the amateur bettors / professional sports fans-statisticians
v
the amateur sports fans-bettors / professional statisticians
v
the amateur sports fans / professional bettors-statisticians
Who will win?

I haven’t read the PDF yet, but I’ll get to it soon enough.

As for the garbage time explanation, that should be easy enough to test: with two minutes to go, look at all games where the gap in scoring was 2-3 points above the line, and the score was between 12 points and 16 points.  Then, look for three control groups, with two minutes to go:
a) the gap in scoring was at least 10 points above the line for the favorite (i.e., darn hard to shave without being blatant)
b) the underdog was leading by between 12 and 16 points (i.e., nothing to shave, but in the same boat as potential shavers)
c) I guess another place to look is that the favorite is 2-3 points BELOW the line, and is leading by 12-16 points (i.e., unaware of the line)

Do any of these four show differences?

Friday, July 27, 2007

A writer who understands odds!

Heyman, pp 66-67 of this week’s SI, on the odds of ARod going to various teams:

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Monday, July 23, 2007

The fallacy of Pythagorean

Credit SABRMatt with opening my eyes to the impact.

Suppose you have a game like yesterday:

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Thursday, July 12, 2007

Median ERA?

There was a discussion on Baseball Fever about using median ERA, because one bad game can really kill you in ERA.  I wrote the following:

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Monday, July 02, 2007

Sports Economic Papers

This was sent to me recently.  I haven’t looked at any yet:
http://ideas.repec.org/s/spe/wpaper.html

Thursday, June 21, 2007

Translating homeruns

Patriot gives us a good introduction on translating (rescaling) stats, focusing on the HR, which if you cut right to the chase is based on this:

New HR = HR/(PF*RPG)*9

In essence, Patriot is scaling it linearly to runs per game.  So, 25 HR in a 2.5 RPG environment would scale to 50 HR in a 5.0 RPG environment. If we run the Markov calculator:
http://www.tangotiger.net/markov.html , we see that 0.66 HR hit in a 2.5 RPG environment (set AB=51, or multiply all the default numbers by 27/41) would be equivalent to 1 HR in 5.0 RPG.  (Note: the run value of a HR, while fairly stable, drops by about 5%.)

What if we go to win values instead?  Using PythagenPat, the win value of a HR is .133 wins in a 5.0 RPG and .21 wins in a 2.5 RPG environment.  That 1 HR in a 5 RPG environment is worth .133 wins.  And, how many HR in a 2.5 RPG would be worth .133 wins?  0.63 HR.

As you can see, both approaches give a fairly similar number, and is a bit different from the 0.50 HR that Patriot would propose.  However, I chose rather extreme environments, and perhaps in more realistic extreme environments, we won’t find such differences.  Trying a 3.5 RPG environment, Markov gives the equivalency as 0.82 HR, and PythagenPat says 0.79 HR.  Patriot’s approach would have said that 0.70 HR in a 3.5 RPG environment would translate to 1.00 HR in a 5.0 RPG environment.

Thursday, May 24, 2007

Odds of making the playoffs

There are at least two sites that track daily the chances of each team of making the playoffs.  CoolStandings.com even offer two flavors, one the “smart”, and one the “dumb” (presumes a prior of .500 for each team).

The Yanks, as far behind as they are, have a 40% chance using the BP prior (i.e., whatever PECOTA thinks they are), a 30% chance using the Smart Cool Standings prior, and a 15% chance if they were a true .500 team in a league of only .500 teams ("dumb", or more accurately, clueless, prior).  The Houston Astros, virtually in the same spot as the Yanks, have a 4% chance according to BP, 6% according to the Smart Cool Standings, and a 15% chance according to the clueless Cool Standings.

It’s a remarkable difference of how much the true talent of a team can impact their chances of making the playoffs, given that they are both equally, and so far, behind.  Looks like Clemens picked the right team, between the two.

Monday, April 30, 2007

If a pitcher pitches a brilliant game, is he likely a good pitcher?

I’ve always thought and written that when a pitcher pitches a brilliant game, he looks like Cy Young and when that same pitcher throws a stinker of a game, he looks like Sy Epstein (our old family lawyer).

Naturally, I also wondered, when a pitcher does pitch an excellent game, what are the chances that he is a very good pitcher, an average one, a poor one, etc.  I did some quick sims to get some idea and here is what I found.

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Thursday, April 12, 2007

Groups of Players and Regression Toward the Mean

I want to talk a little bit about a misunderstood or perhaps overlooked concept in statistics as it relates to baseball (or perhaps baseball as it relates to statistics) and why it is important.  One of the hard-core stat guys who frequent or lurk on this site may have to help me out with some of the nuts and bolts but I think I have a pretty good handle on the gist of the matter.

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Friday, March 30, 2007

Mean, Median: Meandian?

Maybe a couple of you math students can help me.  In the past, I would go through the ballots, and drop 1% or 2% of the obvious junk ballots.  They’re easy enough to spot, but take a bit of time to setup.  I’m thinking of another way to do it:

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Thursday, March 08, 2007

The Four Horsemen

Studes follows the Voros approach in describing some players.  It is in fact Voros’ approach that allowed me to create aging charts.  (See Legend at the bottom)

As you can see, each rate describes something specific.

Now, there’s no reason that you must look at things this way.  It assumes a certain independence that perhaps is not warranted.  You could for example, look at things in other ways.  Rather than removing HBP from the denominator first, then the BB, then the K, then the HR, you can remove all four right away.

So…

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Thursday, February 22, 2007

Help: Solving Polynomial Equations

This is pure math, so anyone who can help me will have my gratitude.  Here’s what I need to solve:

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Thursday, February 08, 2007

Will A-Rod Win a World Series?

Nate has a quick look at ARod’s Chances of Winning the World Series.  It’s based on the likelihood that he will always be on one of the best teams in the league, which I think is being optimistic.  It also assumes that such a team will have a 1-in-8 chance of winning the World Series, if it makes it into the playoffs, which is definitely pessimistic. 

The continual use and misuse of WARP disappoints me.  WARP doesn’t measure what it purports it does.  Don’t get me started.

Anyway, I’ve got the chance of a true 97-win team winning the World Series to be 14%, a 92-win team winning the World Series as 9%, and an 85-win team at 3%.  If we give him odds for the next 8 years of 14%, 12%, 10%, 8%, 7%, 6%, 5%, 4%, that gives us the Odds of him winning in at least one of those years as exactly 50%.

Completely different ways of looking at it.  And Nate and I end up with the exact same results.  Is Vegas taking any action?

Wednesday, January 10, 2007

More Clutch

In this blog entry, Charlie Pavitt looks at hypothesis testing and clutch.  I made a couple of comments in that thread, most notably that you can achieve a correlation coefficient of .999 if two things have even the slightest possible relationship. 

In the BTF thread linking to the Pavitt entry, Wille Keeler asked:

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Thursday, January 04, 2007

Preselection and postselection

I meant to criticize Jeff Sackmann’s recent article, which selects the top 5 starters on each team, after the fact, but Fifth Outfielder did it clearer and better than I would have.  You *must* select before the fact.

Thursday, December 21, 2006

Dolphin Rankings

Many of you probably don’t know that Andy does sports rankings.  Unlike most black box seers, he actually gives you the nitty gritty details.

Tuesday, December 19, 2006

Ratios or Rates?

I am trying to convince JC over at Sabernomics that there is a huge difference between using GB/FB ratio, FB/GB ratio, and GB/(GB+FB) or GB rates.  Head on over there.  Below is a summary of my posts.

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Monday, December 18, 2006

The Odds Ratio Method

Pure math post on how to calculate the expected matchup rates.

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Friday, December 15, 2006

Maximum Likelihood Estimation

Doug Drinen continues the sportsamatics discussion, this time on MLE, with part 2 here.