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Baseball Primer Newsblog— The Best News Links from the Baseball Newsstand
Tuesday, May 20, 2008
This piece will be an analysis of Clay Davenport’s EqR and EqA, and attempt to break down how they work and what their true nature. As such, it is an opinion piece, and is critical in nature. It should certainly not be construed as a neutral presentation of formulas as the last piece aspired to.
...The most important to thing to understand about the structure of Equivalent Runs is that it is essentially a linear weights formula. It is difficult for some people to recognize this from just taking a glance at the formula. However, if one really takes a look at the formula, you’ll see that the only source of non-linearity is the treatment of stolen bases and caught stealing. The denominator of RAW is PA + SB + CS. If SB and CS are both zero, then the RAW denominator cancels with the multiplication by PA, and the formula is 100% linear.
There are strong points for linear run estimators, and there are also strong points for non-linear run estimators. Which class of estimator you should use depends on what you are trying to measure, and both have their uses in sabermetrics. However, it makes no sense to have a formula that is dynamic only in its treatment of stolen base attempts. Of course the value of a SB or CS is dependent on the overall context in which they occur. So is the value of a single, a homer, a walk, or any other event.
All that...and a “Big Bad Baseball Annual” mention!
Repoz
Posted: May 20, 2008 at 08:43 AM | 20 comment(s)
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*hands firmly in lap*
FWIW I try to do that with many rate stats that purport to represent all offense (convert to runs per out).
Tango flipped out awhile back when I did it as a quick test of some stat someone was peddling
"You can't do that!!!" he posted.
He was both right and wrong, he was right because a stat might be "good", but without a 1:1 relationship with runs simply scaling it up could lead to major distortions.
He was wrong because in the specific example, the rate stat actually scaled up beautifully on a 1:1 ratio (The guy trying to peddle a new rate stat was actually 90% of the way to yet another run estimator...)
If you're implying that he was too mathematical, you're wrong. The mathematics make up the heart of the argument. Of course, EqA also asks you to "simply skip over the math and assume [it] is correct."
This isn't directed at you Dr. Memory, but is anybody else bothered that taking a derivative is too complicated for a huge segment of the educated population? Do colleges require liberal arts/social science majors to take calculus?
That probably depends on the College, I know at least three Universities which had no requirements that such majors take calculus.
As others have noted, EqA is essentially OPS/3 with the SB adjustment, also adjusted for park. I believe that Clay intended this as more of a presentation stat rather than as a heavy-duty analytical stat - and as a presentation stat it works very well.
-- MWE
Ezzackly. This is pretty dense, and for me, he skipped steps I needed not skipped. I didn't get far because I figured he'd keep skipping steps, so then I'm just doing what McCoy suggests, and I agree that math is the point. (The writing errors didn't help either.)
In short, it's not the math that bothered me, it's the assumptions with which I am not familiar that stalled me.
This isn't directed at you Dr. Memory, but is anybody else bothered that taking a derivative is too complicated for a huge segment of the educated population?
N.p. Most folks, though, even if they learned calculus, don't use it much in their everyday life, and just like the stats and the chem and speech, it goes away if it isn't used. So it doesn't bother me that I don't recall how to do derivatives OTTOMH... 2x dx yatada yatada I remember, kind of, so I know I could pick it up again if'n I had to. I can still write BAL and COBOL though, for all that good that does me, but the point is I remember them because I used them a lot once upon a time.
In general no and I'd be surprised if they ever did. They do all have distributional requirements which will generally require some classes in "college algebra". (never having had such a class, I've never been sure what college algebra is)
You could of course find tons of 15-year-olds who can integrate your ass into the ground.
And lots of liberal arts/social science majors who know calculus just fine.
And of course huge numbers of math/science (and social science) majors who couldn't write their way out of a paper bag ... are they required to take rhetoric courses?
Don't get me started on MBAs -- no math, no writing, and no reasoning skills!
If my wife didn't have mad math skillz, her MBA program's accountancy and finance courses would've been mighty tough sledding indeed. There were some folks in her program that had a very difficult time with those; I remember her helping them over the phone and at the kitchen table.
I would be shocked if you couldn't take a derivative, or understand an academic paper that utlized differentials. I'm an grad student too, and am a hands on experimental scientist. I rarely do analytical work, but I can still do all the basics when called upon.
And of course huge numbers of math/science (and social science) majors who couldn't write their way out of a paper bag ... are they required to take rhetoric courses?
If I remember college correctly, all students, regardless of major, were required to take at least one writing-intensive course.
The most successful scientists I know can write and argue circles around your average attorney or even lit major. The most successful attorneys I know wear their inability to understand mathematics and science like a badge of honor - "this grotesque deformity looks good on me!"
Anyway, its just my observation, a pet peeve, but probably not a big deal in the grand scheme of things.
You may be giving me a little too much credit, but I could probably get by.
My school had a strong social sciences department, particularly economics and management, and a week liberal arts, but everyone was required to take calculus, physics, chemistry, and biology. It has been 30 years since I graduated, but I imagine they still require it.
I went to UC Berkeley, and I had no such requirement. I took calculus anyway, never used it, and basically remember none of it as a consequence.
As for this article, doesn't it suffice to just know *what* a derivative is? If you understand the concept, you can just trust that Patriot did not make a mistake in taking the derivative and use the formula he writes down.
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