The Dome Effect: Is It Real? Has A Journalist Ever Taken A Stats Class? What Is Reality Anyway?

Submitted by Brian on March 26th, 2013 at 11:33 AM


mah depth perception noooo

One of the reasons I'm not too happy to get Kansas in the Sweet 16 is where the games will be played—Jerryworld—combined with Kansas's #1 strength—Jeff Withey going grrr aargh and depositing your shot in the eighth row. Domes have a reputation for being poor environments to shoot in. Meanwhile, the alternative to shooting is challenging this guy.

But just because something is supposed to be true does not mean it is so. Reasons are applied to random chance all the time. Does being in a dome really kill shooters? I wish I had an answer for you without painstakingly combing through every dome game in the NCAA tournament since forever. The data is thin, contradictory and oft-polluted by what can only be termed a journalist's approach to statistics. After googling every which way for any take on the subject, I've come out the other end possibly less informed than I started.

The best I've got: the WSJ published an article in 2011 that appears to be the most comprehensive tackling of the issue. It showed that from 1997-2011, Final Four teams hit 32% of their threes and 42% overall, both four-point drops from—ugh—the four FFs held before the dome came into vogue. Or we could take thousands of games of data instead of 12, WSJ. And maybe account for the fact that the three-point line moved back in 2008-09. Guh.

/shakes fist at journalism school

For what it's worth, Statsheet shows that three-point shooting held steady at around 34.8% from 2003 to 2008 and around 34.2% after the line moved back. I'd imagine tourney teams are on average slightly better than that, so 32% over 15 years represents a small but probably real negative effect that may or may not be caused by domes instead of various other factors that apply to Final Fours like your hand shaking nervously for an hour before the game. "Other factors" didn't impact 12 games almost 20 years ago, FWIW.

KSRCollege put together a chart covering the "open dome"—ie, court on the 50, not in one endzone—era the NCAA instituted in 2009. (It appears Jerryworld is configured with the court on the 50.) It found three point shooting averages dropped from 36% (for the season) to 32%, free throws from 73% to 67%, and eFG from 51% to 44%.

Caveats are rife. For one, the KSR post has a nine-game sample and the WSJ article is rage-inducingly sloppy. For two, some of these effects may be due to the level of competition. For three:

At first glance if you compare the season percentages to the in-game percentages you’d think that all teams are shooting poorer than their season percentages, but this is not the case.  There are three severe outliers taking down the entire sample; 2011 UConn (twice) and 2009 Villanova.  But, when you see their season percentages you’ll see Villanova was an average three point shooting team and UConn was a terrible three point shooting team, so it’s not hard to believe these two teams would have bad shooting nights.  All other Final Four participants in the “Open Dome” era have shot right around their season percentage, so this leads me to believe that distorted sightlines have less to do with the low point totals than I originally thought.

While I'm not sure I agree with the idea that a poor shooting team will be more affected by the depth issues presented, at least this passage underscores the scanty amount of data we're working with.

Other poorly-assembled nine-game samples show no dome effect.

In 2009 and 2010, the NCAA used all three different setups to contest the eight regionals: regular basketball/hockey arenas; traditional domes, with the court set up in the corner of the football field, and the stadium configuration, with the court built on a platform at the center of the football field.

Here is how the shooting stats broke down in those games:

Arenas (nine games): 42.8 percent, 455-of-1,064.

Traditional domes (nine games): 43.1 percent, 444-of-1,030

Stadium setup (six games): 42.4 percent, 290-of-684.

Essentially, there was no distinct statistical variation among the various types of courts.

This study is also tiny and doesn't even bother to separate out threes and free throws, instead hurling everything in one statpile ranging from dunks to prayer heaves. So it's far from definitive itself. Despite that, Mike DeCourcy appears to run it every year without bothering to update it and reference it whenever the topic comes up. No wonder he gets in fights with Kenpom.

Last year, teams didn't seem to have much problem. OSU, Louisville, and Kansas hit exactly 36% of their threes; Kentucky was at 38%. This is probably why there was a flurry of articles about shooting in a dome before that Final Four, but not after.

So. We have a pile of shifty data. Overall I'd suggest it suggests there is a small dome effect that hurts shooting based on the WSJ numbers, which are the closest thing to a real sample we've got. This is advantage Kansas, which takes relatively few threes and forces a lot thanks to Jeff Withey. Probably, anyway. The effect isn't big enough or solid enough to be fate.

Ugh. This post. Just like a younk man who thinks Standard Deviation is a Christian goth metal band coming in for a low-sample size study. I am zo unzatisfyed.



March 26th, 2013 at 11:46 AM ^

In all fairness to journalism school, I actually started as a journalism major, and the first thing they said on the first day of my first journalism class was: "most journalists didn't major in journalism."

So there you have it.


March 26th, 2013 at 11:50 AM ^

I'm honestly not that worried about Kansas after seeing Withey play against a less physical UNC... so long as the McGary monster stays out of foul trouble, we should be able to sneak by without having to worry about the shenanigans that is the "Dome" effect.  Also, nice Rounders reference at the end there. Vant a cookie?


March 26th, 2013 at 12:22 PM ^

Kansas completely dominated that game.  The only reason they went down in the 1st half was that their shots kept rimming out.

McGary had 4 fouls in 3 of the 4 games against Indiana and MSU, including an 8 min/ 4 foul performance last game against Zeller.  He's probably going to be in foul trouble.


March 26th, 2013 at 12:39 PM ^

McGary's "rise to dominance" has come against two of the smallest teams we've faced all year. So while he's shown (in a 1 game sample size) that he is able to abuse a small, unathletic team, and that he is able to out-hustle an athletic hustling squad, he has yet to show he can be effective against a pure center.

But anyways, here's to hoping his rapid ascent continues.


March 26th, 2013 at 12:40 PM ^

McGary had a total of 2 fouls in the two games against MSU, but he did have 4 in both games against IU.  Withey is not a skilled offensive player though.  He gets most of his points on putbacks and lobs.  He does have a decent right handed hook over his left shoulder, but his offense alone will not win the game for Kansas.  And Young, whom Brian mentioned as a bad matchup for Glenn Robinson, is far less skilled than Withey.  This really is not that bad of a matchup for UM.


March 26th, 2013 at 12:55 PM ^

I will give you Zeller, but he is also a future lottery pick. Both Payne and Nix averaged 10 pts in 2 games against us, hardly dominant performances.  Evans had 12 points on 12 shots against us in the BTT, and all of those players are much more skilled offensively than Withey and Young (well maybe not Evans).  Withey will probably be a dominant force defensively, but McLemore, Releford and Johnson are the threats offensively to worry about, IMO.


March 26th, 2013 at 3:01 PM ^

The thing about Whithey not being a huge offensive threat is somewhat due to his reputation as a shot-blocker defensive player. He's taking 9 shots a game and drawing over five FTAs. His ORB numbers (2 per game) don't explain all that, and he's not exactly playing with Jason Kidd either. 14 ppg is pretty good - not far off Zeller's 17.  He's not going to post up every play like Zeller did, but he can do some damage too.  His biggest impact will be on defense, but will need Morgan, Horford and McGary to all play tough D to account for Whithey.

As for Young - he's not really a scorer but he can matchup well with Robinson's athleticism.  He's skinny, but he rebounds really well (more ORB than Whithey) - and boxing out hasn't been Robinson's strong-suit.  If Young grabs 4+ offensive rebounds that's very bad news for Michigan.


March 27th, 2013 at 10:20 AM ^

Definitely not saying Kansas didn't dominate that game.  I'm just making the point that as long as we can sort of stymie Withey and pull that matchup to more or less of a draw, then I like our chances.


March 26th, 2013 at 11:53 AM ^

all the players wil have enough practice time in the dome setting to adjust their shots accordingly, although the depth perception could be an issue for some also guessing nerves have quite a bit of influence as well


March 26th, 2013 at 11:57 AM ^

As long as we keep getting referees that understand that the thing teams like Wisconsin play IS against the rules we'll be fine IMO. That's the biggest reason for our return to greatness - getting away from the officials who truly believe "no blood no foul" is a correct term when calling a game.


March 26th, 2013 at 11:58 AM ^

Hopefully Nik is used to wide open sightlines from all those shooting drills in his backyard.... though I seem to remember some fencing beyond the court, there was also wide open sky IIRC.

Rick's American Cafe

March 26th, 2013 at 12:07 PM ^

It's not a "Dome vs. Arena" question as much as it is an "open space & background" question.  From the shooter's perspective, playing in a dome is not much different than playing in an arena.  In both scenarios, you've got a glass backboard, and tons of open space behind the basket.

The bigger difference is "Dome/Arena vs. Gym".  There is a big difference there.  Gyms have a nice, solid, background behind the basket.  Arenas/Domes don't have that background, and it's a bit disorienting.  In high school, we played most of our games in gyms, but there were a handful in arenas (and I even once played in Crisler, when my intramural team made it to the Michigan campus finals.  Good times, haha!).  I found it disorienting to shoot in arenas, and several teammates felt the same way.  It's not a huge deal, but you do have to adjust your frames of reference, and takes a good amount of shooting around to really adjust from gym to arena/dome.  But differences between an arena and a dome?  Probably not so much.  If a dude can shoot in Crisler, then he can shoot at JerryWorld. 


March 26th, 2013 at 3:34 PM ^

Disagree.  The setup at Jerryworld is not going to be like Crisler.  The permanent seats at Jerryworld are very, very far from the action.  There will be huge space in between them and the court, where some temporary seats will be placed but it will definitely not duplicate the intimate setting of an arena. 


March 26th, 2013 at 12:48 PM ^

Yesterday I did a similar study - gathering all 80 Sweet Sixteen teams from 2007/08 through 2011/12, comparing their season scoring average, their tournament scoring average (non-football stadium sites) and their scoring average for tournament games at football stadiums.


The sample size isn't as large as I'd like, but a few interesting points emerged:

The last five years, there have been 11 basketball-arena sites hosting the second weekend of the tournament and 9 football-stadium sites.  

Overall, scoring is down 8.1% the second weekend vs the first weekend, and down 8.4% from a team's regular-season scoring average.  
The true basketball sites have a larger drop in scoring:  -9.9% from tournament average, -10.5% from regular season average.  
Football stadiums see a drop of only -6.2% and -6.3%, respectively.
All Final Fours have been played in football stadiums over the past five tournaments.  
Scoring is down 15.0% from previous tournament performance and -14.9% from regular season performance.
Ford Field -15.74% (tournament) -10.73% (reg season)
Lucas Oil -14.81% (tournament) -15.40%  (reg season)
Reliant Stadium -11.67% (tournament) -13.19% (reg season)
Superdome -11.39% (tournament) -14.11% (reg season)
Alamodome  -8.04% (tournament) -9.15% (reg season)
EdwrdJones Dome  -7.84% (tournament) -10.40% (reg season)
Phoenix Stadium  -4.11% (tournament) +4.77% (reg season)
Georgia Dome  +9.11% (tournament) +8.21% (reg season)
Also interesting was that in 4 of the past 5 years, out of the Sweet 16 teams, one of the top two teams with scoring averages increasing most over regular season averages made the Final Four.
Equally interesting was that in 4 of the past 5 years, one of the bottom two (S16) teams with scoring averages dropping the most from the regular season averages also made the Final Four:
2008 UCLA (#1) Reg Season: 74.0 pts Tourney: 60.5 pts
2010 Duke (#2) Reg Season: 78.0 pts Tourney: 70.5 pts
2011 Kentucky (#1) Reg Season: 76.4 pts Tourney: 65.0 pts
2012 Kansas (#1) Reg Season: 75.0 pts Tourney: 63.5 pts
2008 UNC (#16) Reg Season: 88.7 pts Tourney: 110.5 pts
2009 UConn (#15) Reg Season: 77.3 pts Tourney: 97.5 pts
2011 VCU (#15) Reg Season: 71.5 pts Tourney: 81.0 pts
2012 Kentucky (#16) Reg Season: 76.7 pts Tourney: 84.0 pts

El Jeffe

March 26th, 2013 at 12:39 PM ^

If there is a dome effect it is likely to be (1) incredibly small; and (2) completely washed out by other non-dome related factors. That is, the dome signal:other stuff noise ratio probably hovers somewhere between zero and very small.

The main thing is that shooters don't aim the ball a certain distance and gauge that distance based on cavernousness of background. Shooting is probably 97% muscle memory based on the brain's knowledge of the distance from the feet to the front of the rim, which is where the eyes focus anyway.

I'm worried that M will not shoot well against KU, but not because of Jerryworld.


March 26th, 2013 at 1:00 PM ^

I took a tour of Jerryworld last year.  As part of the tour, you have the opportunity to go down on the field and throw a football around (for as long as you want, it's actually pretty awesome).  We were there during the day and played catch for a solid hour and I was shocked at how difficult it was to pick up a thrown ball when looking back at the windows at either end of the stadium.  Also, the place is so large that you get a very disoriented feeling anytime you look up or into the distance, particularly while running.  It's an amazing place that is simply huge. However, from my very limited experience it seems like an awful place to play (or watch) a basketball game and I wouldn't be surprised to see both teams struggle.

I'd be curious to see if the various shooting stats at Jerryworld are any different than at other domes.



March 26th, 2013 at 10:29 PM ^

I also took the tour and am thinking Jerryworld might be an outlier in the world of domes.  

The place is gigantic and ridiculous and the Cowboy Cheerleader locker room is just as nice as the player's and it smells like toxic poof hairspary.

Total outlier.  



March 26th, 2013 at 1:39 PM ^

Has anyone read this article in Grantland about the Miami Heat, and thought the decription of Miami's offense sounded like Michigan's?

Money quote:

"League observers used to talk about Orlando's four-out/one-in system, with four shooters surrounding Dwight Howard in the post or on the pick-and-roll. Miami and Erik Spoelstra have one-upped that by often playing a five-out system, with all five guys moving around the 3-point arc as the Heat run through a series of rehearsed actions while hunting for gaps in the defense."

Is this what Beilein is going for?  If so, does Michigan really need to play "big"?  Or does it just need its athletes to stick around until they get the system?  If the latter, are Beilein's schemes doomed by their success?  In other words, would his schemes only work fully if his players all stayed for 3-4 years?   


March 26th, 2013 at 2:10 PM ^

I'm an engineer in the auto industry, and the lack of "proper" stats use is pretty staggering. And this is among engineers! Who should know better. When not  among science types the lack of stats knowledge I assume gets even worse. If you give me a data set and the story you want it to tell, I can make the stats do that.

I guess the moral is, good stats are hard to find. Not just among jounalists.


March 26th, 2013 at 2:51 PM ^

To me. Most players at this level have played in so many different arenas and environments that I have a hard time believing sightings would mess most guys up.

Marley Nowell

March 26th, 2013 at 4:27 PM ^

I remember hearing Steve Kerr on a podcast a while back talk about dome effect and thought it was a real reason teams were struggling hitting shots in the FF.  He cited factors such as sightlines and open air flow.


March 26th, 2013 at 5:06 PM ^

Any studies on how a giant scoreboard (one that looks larger than the court) affects shooting percentage?

I mean, this place is just ridiculous.


March 26th, 2013 at 7:40 PM ^

Oh my Lord.  You're not lying, that "side panel screen" really is larger, considerably, than the friggin' court.

And why the hell would anyone buy seats to be at that place?  I guess the scoreboard is there and will obviously help viewing purposes but the players are going to appear as ants, it looks like, whereever one sits.