WBB: Stanford 78 Colorado 69 - Printable Version
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RE: WBB: Stanford 78 Colorado 69 - 2006alum - 01-26-2019
Thanks for the insightful posts - I really had just wondered on a lark because it's so noticeable in tennis and takes time to adjust. I'd definitely be curious to see data on this for Buffs home and away games over time. If indeed we're talking about drag differentials that can alter a shot's arc by 6" to a foot, that could definitely alter basket rates, not just at the margins.
RE: WBB: Stanford 78 Colorado 69 - qwerty49 - 01-26-2019
Just look at the pitching stats (which by definition address hitting also) for MLB teams playing at Colorado and you would conclude altitude affects both a thrown and a batted ball.
So one can conclude a 3-pt basketball shot is affected to some degree as well.
And it seems we did adjust somewhat in the second half.
RE: WBB: Stanford 78 Colorado 69 - oldalum - 01-26-2019
The comparison is complicated by the fact that basketball shots travel much shorter distances than baseballs.
One loosely reported empirical analysis of free throw percentages at altitude vs. lower locations found:
When we compared how visiting players performed away from and at Denver, the difference became even larger. Outside of the Pepsi Center, these players shot 76.0%, but at this higher elevation, they shot just 74.5%. Once again, our results were significant, yielding a p-value of 0.0143. https://harvardsportsanalysis.wordpress.com/2011/05/18/does-altitude-affect-free-throw-percentage/
RE: WBB: Stanford 78 Colorado 69 - BostonCard - 01-27-2019
(01-26-2019, 06:39 PM)M T Wrote: I ran across an analysis that uses some NBA statistics mixed with some physical analysis (it was a follow up to this May 2015 article). It isn't a research paper, so it wasn't peer reviewed and may have errors. He begins talking about drag and altitude about 2/3 way down. But, talking about sea level, he says "The drag force should only alter the path of a free throw by about 6 inches, which is probably at the limit of the SportVU system's precision." I'm not quite sure why 6 inches wouldn't be extremely visible. If he means that the shot would be 6" shorter due to drag, then that would be immediately obvious except that the players compensate for it. If he means that the highest point of a free throw's path would be 6" higher after compensation, I think that would be pretty obvious.
I imagine that SportVU, which is based on cameras around the stadium, digitizes each action so that for any shot you can calculate position (in three dimensions) and a vector of velocity (angle and speed). From that, you should be able to calculate the effect of forces, including drag, on the ball. I am a bit surprised that the error would be as much as six inches, but of course it is not zero, and there almost certainly is some imprecision in the digitization process.
SportVU is mostly used by teams as an analytics to try to determine optimum plays to run (such as which player should be shooting and from where) and probably doesn't need better than 6 inch resolution, but the cameras are all high-speed, high-resolution cameras.
Fun fact about SportVU: "SportVU was created in 2005 by Israeli scientists, Gal Oz and Miky Tamir,[6] who had a background in missile tracking and advanced optical recognition.[7][8] They had previously used some of that same science to track soccer matches in Israel."
(from the wiki)
BC
RE: WBB: Stanford 78 Colorado 69 - oldalum - 01-27-2019
(01-26-2019, 06:39 PM)M T Wrote: There are concepts we fans have (like "too many steps") that aren't quite what the NCAA rules use. But if you keep reading the CARDboad, we might get it right._________________________________________________________________________________________________
The bounce should be roughly the same, not because of how air pressure affects the bounce, but because the amount of bounce is part of the definition of a legal ball.
NCAA WBB rules
Art. 7. The air pressure that will give the required reaction shall be stamped on
the ball.
What I was trying to say was that if you inflate a basketball at sea level to a specific pressure as measured by a typical hand pump, then bring that same basketball to Denver and inflate it to the same measured pressure, the bounce should be the same (factors other than change in altitude being equal). I think you are saying that the reason the bounces of basketballs used in NCAA women's games are the same in all arenas is that their pressures are adjusted such that they are the same. I do not know whether this is true, but my initial guess is that whoever checks at NCAA games whether the balls are inflated correctly does not do so by measuring the actual bounce to verify it is within the specified limits, but does so by checking that the pressure matches that stamped on the ball. My interpretation of the NCAA rule you cite is that it is a specification to the ball manufacturers that they are to manufacture their balls so as to meet the specified parameters and to stamp on the ball the pressure required to meet those parameters. But the height of the bounce probably depends on the surface it is bouncing on, too, which would argue for actually measuring the bounce at games. Does anyone know what is actually done at Pac-12 games?