The GAA Battle

I just sent a brief note to USCHO's Stats department. I'm probably not only wasting my time, but obsessing a bit much.

I understand that GAA is typically only *represented* in stats to the second decimal place. But the fact that David McKee's GAA *rounds up* to 1.43 (1.427363078875) and Matti Kaltiainen's GAA *rounds down* to 1.43 (1.43060319585) tells me something's wrong with the way you're listing them on the stats page. It's one thing to *list* them both has having a 1.43 GAA, that I understand. I simply dispute whether it's accurate to list them as being *tied* by virtue of those "matching" 1.43 GAAs.

Beeeej

Yes. You are obsessing too much. And this coming from me.

I'm a black kettle!!

Thanks, pot.

Beeeej

To get an idea, McKee's GAA would be exactly equal (to several decimal points) to Kaltiainen's had McKee played 2:51 less, or had Kaltianianen played 1:49 seconds more. So we're talking a margin of error of less than what a goalie could be pulled for delayed penalties and extra man attempts. While the numbers are big enough (i.e. not a few seconds) to argue that McKee may indeed have played a tiny, tiny bit better, I also can't blame them for calling it a tie.

I can't, either - in fact it's probably an algorithm rather than any conscious choice on USCHO's part. I don't have to like it, though. :-{)}

Beeeej

[Q]So we're talking a margin of error of less than what a goalie could be pulled for delayed penalties and extra man attempts. [/Q]

Does the time the goalie is off the ice for delayed penalties really come out of his time played stats? (I'm sure you're right that it does...I just never realized that it did.)

Thanks.
Andy W.

[Q]andyw2100 Wrote:

Does the time the goalie is off the ice for delayed penalties really come out of his time played stats? (I'm sure you're right that it does...I just never realized that it did.)[/q]

I could have sworn it didn't, but I couldn't find anything about GAA in the NCAA rules.

Hasnt Matti only played half the total time McKee has?

[Q]French Rage Wrote:

Hasnt Matti only played half the total time McKee has?[/q]

David has played 1261:04, and Matti (who has been sharing goaltending duties with Cory Schneider, who happens to be 4th in the country in GAA) has played 796:52

The Kaltiainen/Schneider duo is having the same type of success that, recently, Howard/Doyle and Underhill/LeNeveu had.

Yes, it's obsessive. But does one more decimal place really make a difference, on GAA or save pecentage? As others noted, for GAA the rounding difference amounts to to perhaps 5 minutes played more or less if you carry the season out to three deccimal places.

Remember the term JND, or just noticeable difference? I think if you carry it out one more decimal place, you've gotten beyond what's noticeable.

With save percentage, a third decimal place implies precision that isn't matched in reality because the stat-keepers are going to miss the odd save here or there, or give credit to a shot gloved just outside the cage. McKee has 432 saves on 462 shots allegedly on goal, or .935. (actually .9351 so it rounds legitimately to .94). But if the scorekeeper misses one save per game, which wouldn't be hard, it's 412/442=.932, and if the scorekeeper was overly optimistic and counted one shot each game as a save when it was outside the cage, it would be be 452/482=.938, still rounding to .94. So there's a danger in thinking that because you can move the decimal places out, you should.

I'd say if two goalies finish the season with a .95 save average or a 1.40 GAA average, it's a tie, regardless of whether they're really .951 and .952 on saves, or 1.399 and 1.401 on goals. It's a tie.

Maybe we're on this thread because game clocks now count the final minute in tenths. Really, it should only be the final ten seconds in tenths, which divides the final ten seconds alone into 100 components. On the court for the players, coaches, and fans, it makes sense to go to tenths at 1:00 remaining and not :10 remaining because if you glance up and see a 1 and a 5, you might not know if it's 15 or 1.5 seconds remaining.

But are sports that granular as the final minute in 600 segments? I think there should be a journalist's code of ethics (oxymoron, right, like legal ethics?) that says you only cite the tenths in the last five seconds. The fact that morons on TV do it doesn't mean the print media with hopefully more brains if not such whitened teeth should follow suit. Bill Russell was great expounding on whether the clock had a long or short two seconds left in the fourth quarter. Other than that, there isn't a JND.

Let's get back to something more useful, like Cornell's chances of getting a #1 seed.

wrong thread

[Q]billhoward Wrote:


Remember the term JND, or just noticeable difference? I think if you carry it out one more decimal place, you've gotten beyond what's noticeable.

[/q]

Back to intro psych for you, Bill. :p

I may not play one on TV, but I am in fact a psychophysicist in real life, and you've utterly abused a technically precise piece of jargon here. Weber is rolling in his grave as we speak.

The concept I think you are looking for here is one of significant digits, not simulus intensity.

Pedantically yours.

jh

[Q]billhoward wrote:
I'd say if two goalies finish the season with a .95 save average or a 1.40 GAA average, it's a tie, regardless of whether they're really .951 and .952 on saves, or 1.399 and 1.401 on goals. It's a tie.[/Q]
So, .9451 and .9549 would be a tie (though separated by .0098), but .9449 and .9451 would produce a clear winner? This makes no sense at all. Whoever has the best save percentage (or GAA), no matter how many decimal places it takes, is the person who has the best percentage.

One can carry the math out to four, five, six decimal places to produce a goaltending number that's just slightly different from another ... but the margin of error is higher (for save percentage certainly) because of the vagaries of stat-keeping.

That's why three decimal places of precision for GAA is enough (1.xx) and two for save percentage (0.xx) where it's possible to be off by several shots a game on shots that may or may not have been saves.

Ditto for, say, points and assists per game. Does the ref always get that second assist right?

This reminds me of the American League batting title race of 1910 (who could forget it?) between Ty Cobb and Nap Lajoie. The winner of the batting crown was to receive a new car, and because Cobb was so hated, when Lajoie played in St. Louis on the last day of the season, the Browns' manager ordered his third baseman to play on the outfield grass to allow Lajoie to bunt for hits all day long in order to pass Cobb. Lajoie went 8 for 9, but even with the help, he lost the race to Cobb with batting averages of .384944 to .384084. What's the point of all this? Even though at the time, it seemed like Cobb won by going to the fourth (and generally unseen) decimal place, historical research ultimately has shown that Lajoie actually won the race, .384 to .383. Cobb still got the car, and the research was done after Lajoie's death, so I'm sure it's hardly consolation.

Didn't I answer this last week? Yes, it's counted as "Empty Net" when the goalie comes off for a delayed penalty. No, he doesn't get credit for playing goal when he's sitting at the bench.

[Q]billhoward Wrote:

One can carry the math out to four, five, six decimal places to produce a goaltending number that's just slightly different from another ... but the margin of error is higher (for save percentage certainly) because of the vagaries of stat-keeping.

That's why three decimal places of precision for GAA is enough (1.xx) and two for save percentage (0.xx) where it's possible to be off by several shots a game on shots that may or may not have been saves.

Ditto for, say, points and assists per game. Does the ref always get that second assist right?[/q]

First off, we're NOT talking about SV%. There's no margin of error for GAA. The number of goals allowed is known and the time he's played is known.

Second, regarding SV%, would you say there's a margin of error on game scores? What if you don't think a goal should have counted, but the ref does? It's still a goal. Just the same, there's an official who counts shots on goal. Whatever he deems a shot on goal is a shot on goal. Those stats don't carry a margin of error; they're official. And since a shot on goal is 1.000000... shot on goal and not approximately one shot on goal, you can, and should, take the stats out to as many decimal places as needed to break a tie.

Whatever is on the official scoresheet, be it shots, goals, assists, or minutes played is all that matters and the only thing ever used to calculate stats, no matter what you happen to think about it.

Bill is arguing false precision as far as I can tell...

Age is arguing that no such thing exists in sports because, as sports fans, we collectively agree to treat numbers veridically, noise and all. Is there noise in the system? Certainly, but we all agree to pretend it doesn't exist.

I gotta go with Age on this one.

A hit is a hit, an at bat is an at bat and a goal is a goal. Do timekeepers shave seconds off the clock, affecting GAA? Certainly. Do homer score keepers inflate shots boosting SV%? Certainly. But for the purpose of records we all agree to pretend it doesn't exist.

Football has perhaps the best example of this convenient fiction with spotting the ball. The ref spotting the ball is inherently inaccurate but we pretend it is an accurate event and then watch as they measure with the chains.

just my $.02

[Q]CowbellGuy Wrote:
First off, we're NOT talking about SV%. There's no margin of error for GAA. The number of goals allowed is known and the time he's played is known.

Second, regarding SV%, would you say there's a margin of error on game scores? What if you don't think a goal should have counted, but the ref does? It's still a goal. Just the same, there's an official who counts shots on goal. Whatever he deems a shot on goal is a shot on goal. Those stats don't carry a margin of error; they're official. And since a shot on goal is 1.000000... shot on goal and not approximately one shot on goal, you can, and should, take the stats out to as many decimal places as needed to break a tie.

Whatever is on the official scoresheet, be it shots, goals, assists, or minutes played is all that matters and the only thing ever used to calculate stats, no matter what you happen to think about it.[/q]
While there's not a margin or error on goals (or at least, not unless its a really contrived scenario), there is a margin of error on time played. Some score keepers take off for delayed penalty goalie pulls, some don't. There's of course a question of a few seconds on that even if you do. Is it when he leaves the net, when the other guy hits the ice, when he leaves the ice? Same goes for end of game empty net scenarios - do you take that out? Usually, but what's the timing exactly? A few seconds here or there different. So while the difference is certainly less than for SV%, there is still a practical margin of error.

That was my point for doing out the time difference that would make them equal (note I didn't do a goals difference).

Sorry to contradict you on several threads today, Age... it's nothing personal!

Of course there's some error from the timekeepers, but whatever's on the official box score, for the purpose of keeping records, is the Word of God, and may be used with as much precision as anyone needs.

[q]Of course there's some error from the timekeepers, but whatever's on the official box score, for the purpose of keeping records, is the Word of God, and may be used with as much precision as anyone needs.[/q]If what you're trying to do is decide on a qualitative level whether goalie A is better than goalie B it's silly to look at the third or further decimal place. But if you want to say who had the better GAA or Sv% stat this year then the official stats are, as Age puts it, the Word of God.

[Q]CowbellGuy Wrote:

Of course there's some error from the timekeepers, but whatever's on the official box score, for the purpose of keeping records, is the Word of God, and may be used with as much precision as anyone needs.[/q]
Until, say, someone goes back and awards the 1910 batting title to Nap Lajoie.

If we carry GAA out to 1.xxx instead of 1.xx, sooner or later we'll have a tie, there, too, that maybe is broken by going to 1.xxxx GAA.

As for save percentage, which others have remarked on as well - why is it listed as 94% not 94.2% on USCHO - one of the two component numbers is suspect. The number of goals allowed is pretty concrete (well, maybe Dartmouth was offside and it shouldn't have counted, but it did). The number of shots at the goalie is rife for potential error because a human is judging them, and from a lot farther away than the refs whose judgment is grist for a lot of postings here already.

The scorekeeper might favor the home team and see shots-just-wide (that are gloved) as saves for the home goalie, or he'll only notice two of the three shots hitting the goalie in a flurry in front of the net, or he'll count all three shots as shots on goal even though the second hit a defenseman not the goalie and the third was gloved wide of the net. Maybe the errors cancel themselves out, maybe not. Once the record book is signed, it's possible to carry the save percentage out to two, three, or four decimal places of precision, but that's not the same as two, three or four decimal places of accuracy. G.I.G.O.

Three and a half decades later, does it matter whether Ken Dryden saved 93.9 percent or 94 percent of the shots that the scorekeeper says Dryden faced? In some ways, it's probably better to remember 94 percent, because it's an accurate enough reflection on his career. Dave LeNeveu I believe was 93.8 or 94 percent on saves, take your pick, and if you go with the 94% number, it says these two remarkable goalies (or extraordinary and merely remarkable) goalies, playing a generation apart, stopped 94 of every 100 shots they faced. If those were in fact Dryden's and LeNeveneu's save percentages, is someone going to say LeNeveu was a better goalie? The difference is something like 2, 3 or 4 saves over the career: 938 vs. 939 saves out of every thousand shots faced.

A lot of this is a philosophical discussion and it's shaped by how you see the world or what your job is. I've had to explain with broad brush strokes to people who want to see the big picture and not have them caught up in minutiae, for instance buying one PC instead of a another because its Winstone score is 28.8 when someone else is 28.1. (Which all gets lost when the bleeping computer crashes every hour because the clock got pushed or some piece of software disagreed with XP and lost.) If I was the timekeeper for Nascar, then, yeah, I'd want the stopwatch to measure fractional seconds out to three places. And if I ever my eyes lasered, I think I'd like the surgeon to work out the cutting patters to about nineteen decimal places.

(True story. My colleague, five-six years ago, goes in for the eye surgery. She's patient No. 1 in the office at 9 a.m. She's waiting. She's nervous. She hears the doctor fire up the computer in the operating room. She hears the Windows 98 bootup chime. She knocks on the door: "Um, doctor, would it be okay if I was your *second* procedure today?"

[Q]Beeeej Wrote:

I just sent a brief note to USCHO's Stats department. I'm probably not only wasting my time, but obsessing a bit much.

I understand that GAA is typically only *represented* in stats to the second decimal place. But the fact that David McKee's GAA *rounds up* to 1.43 (1.427363078875) and Matti Kaltiainen's GAA *rounds down* to 1.43 (1.43060319585) tells me something's wrong with the way you're listing them on the stats page. It's one thing to *list* them both has having a 1.43 GAA, that I understand. I simply dispute whether it's accurate to list them as being *tied* by virtue of those "matching" 1.43 GAAs.

Beeeej[/q]
I'll sign your petition if you go along with mine asking that all scoring stats be on a "per game played" basis, the way goalie stats are done.

I've been shouting into the wind on that one for ages. Gee, I wonder why there are no Cornellians on the Goals Scored leader board? Could it be because we pay several fewer games?! Blah.

Beeeej

[Q]Robb Wrote:
I'll sign your petition if you go along with mine asking that all scoring stats be on a "per game played" basis, the way goalie stats are done.
[/q]
Or, you could use collegehockeystats.com, where all but PPG, SHG, and GWG are on a per-game basis.
[www.collegehockeystats.com]

[Q]RichH Wrote:Or, you could use collegehockeystats.com, where all but PPG, SHG, and GWG are on a per-game basis.[/q]

...and where Matti Kaltiainen is correctly listed as second, not tied for first, in GAA.

Beeeej

By the way, don't you love that our "clutch-and-grab" team is 49th out of 58 teams in penalty minutes per game for the season?

Beeeej

[Q]Beeeej Wrote:

By the way, don't you love that our "clutch-and-grab" team is 49th out of 58 teams in penalty minutes per game for the season?

Beeeej[/q]
we just know how to get away with it ... duuhhhh, c'mon beeeej

and if it weren't for mr. o'byrne we'd be even lower on that list

[Q]ben03 Wrote:

and if it weren't for mr. o'byrne we'd be even lower on that list[/q]

Hey, it's not O'Byrne's fault he's that big. It's just good genes and upbringing.

sure it is ... so i guess this explains his propensity for stupid penalties?

[Q]ben03 Wrote:

sure it is ... so i guess this explains his propensity for stupid penalties?[/q]

Well, some of us have been saying for a while that O'Byrne gets penalized simply because he's too big for his own good.

[Q]Will Wrote:

ben03 Wrote:

sure it is ... so i guess this explains his propensity for stupid penalties?[/Q]
Well, some of us have been saying for a while that O'Byrne gets penalized simply because he's too big for his own good.[/q]
but holding/tripping/interfering your opposition directly in front of the referee is somehow not his fault?
your defense was the case with Stephen Bâby but i'll have to disagree with you for big'ole #2.

 

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