- Roland ---

It's always entertaining listening to guys broadcast the NCAA

Tournament. One radio broadcaster was blatantly making up stats

yesterday, saying that 65% of 3pt shots are rebounded by the offense

and that Jason Kidd shoots 95% from the line at clutch time and 60%

other times. In looking at Jason Kidd and Kobe Bryant and thinking

through a few things, I actually came to wonder whether any 15+ ppg

scorer shoots better than their average under clutch conditions...

DeanO

Dean Oliver

Author, Basketball on Paper

http://www.basketballonpaper.com

"There are a lot of math guys who just rush from the numbers to the

conclusion. . .they'll tell you that Shaq is a real good player but

his team would win a couple more games a year if he could hit a free

throw. Dean is more than that; he's really struggling to understand

the actual problem, rather than the statistical after-image of it. I

learn a lot by reading him." - Bill James - Nice work, I would modify your provisional conclusion just a little bit:

provisionally, it appears that clutch FT shooting is a small or non-existent

effect for almost all players. But there might be a few who have non-trivial

clutch impacts ... Sprewell, Payton, etc. However, it's too early to conclude

that they truly have clutch effects, given the possibility of Type I errors.

--MKT

-----Original Message-----

From: igor eduardo küpfer [mailto:edkupfer@...]

Sent: Sunday, March 21, 2004 1:35 AM

To: APBR_analysis@yahoogroups.com

Subject: Re: [APBR_analysis] Clutch FT shooting...

DeanO:

> >> through a few things, I actually came to wonder whether any 15+ ppg

Ed:

> >> scorer shoots better than their average under clutch conditions...

> >>

> >> DeanO

>

> [...]

>

> >According to Roland's spreadsheet, only four +15ppg players out of 68

shoot

> >FTs at a significantly different percentage in clutch time, two better

and

> >two worse. Top 10 lowest p-values:

MikeT:

> >

> >Team Player nonClutchFTM-FTA ClutchFTM-FTA Diff p

> >MIN Sprewell 209-260 19-30 -17.1% 0.022

> >BOS Pierce 446-534 54-72 -8.5% 0.042

> >ATL Abdur-Rahim 343-393 23-23 12.7% 0.044

> >WAS Hughes 203-251 22-23 14.8% 0.049

>

> [...]

> If we choose a 5% significant level, (5% probability of a Type I error),

Thanks Mike, that's what I was getting at.

> then out of a sample of 68, under the null hypothesis of no difference

> between clutch and non-clutch, we'd expect exactly 3.4 observations to

> show differences with a p-value of less than .05.

>

> This sample of 68 has 4 observations with p-values < .05.

>

> In other words, these numbers look almost exactly like the ones that

> random chance would produce, under the null hypothesis.

>

> So not only do 64 of the 68 show no significant difference, the 4 who

> do appear significant quite possibly may simply be reflecting pure chance,

> and not any true clutch or non-clutch shooting ability.

>

<snip>

>

As it happens, I ran a similar test on last season's 82games clutch stats.

> BUT: small sample sizes. It's only, what, 3/4 of a season? So it would

> be prudent to re-examine this issue periodically.

>

> In statistical terms, our small sample sizes mean that our tests have

> low power, i.e. a high probability of a Type II error. There may

> in fact be clutch vs non-clutch differences there, but we can't detect

> them yet. Let's look again at the end of the year, then next year,

> and the year after that. My informal judgement is that it'd be around

> that point that, if we're still seeing a lack of significant results,

> that we would be able to conclusively say there appears to be no

> clutch FT shooting.

>

The pattern is the same: among 15+ppg players, 5 out of 64 (8%) had clutch

FT%s significantly different from non-clutch FT%s (that is, significant at

5%). Interestingly, Sprewell makes the list for both this year and last.

Player FTm-FTA cFTm-cFTA Diff p

Zydrunas Ilgauskas 354-440 46-72 -16.6% 0.0008

Tracy McGrady 519-645 57-81 -10.1% 0.0193

Shawn Marion 203-244 48-51 10.9% 0.0198

Allan Houston 317-341 46-54 -7.8% 0.0343

Latrell Sprewell 142-174 31-44 -11.2% 0.0490

What else can we do? There are other situations which fall under the

category of "clutch" -- playoff games when one's team is facing elimination,

for example. I made a list of elimination games since 1996, and came up with

173 team-games (game sevens count as two team-games, as both teams are

facing elimination). In those games, 39 different players attempted thirty

or more free throws (spread among more than 1 game, obviously). Four of

those thirty-nine players (10%) posted FT%s significantly different from

their career averages -- I used career FT% in this case for ease. This is

not what I used above, where non-clutch FT% in that single season was used

for the probability calculations.

Player FTm-FTA CareerFT% Diff p

Gary Payton 71- 85 72.7% 10.8% 0.0137

Michael Finley 33- 35 80.2% 14.0% 0.0206

John Stockton 50- 54 82.6% 10.0% 0.0307

Karl Malone 83-124 74.2% -7.3% 0.0429

The whole thing still smells to me like random variation. I am comfortable

with the idea that clutch ability doesn't exist, but I realize there hardly

has been enough testing to make that conclusion. I think that we can

provisionally accept that if clutch FT shooting ability does exist, it is a

small effect.

ed

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