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2017 Great Lakes Analytics in Sports Conference
2017 Great Lakes Analytics in Sports Conference
Definitions
Success: Making shots in basketball, getting hits in baseball,
rolling strikes in bowling, beating par on golf holes, etc.
Fans, coaches, and players may use the term “hot hand” simply
to refer to a player who has succeeded many times in a row.
Statisticians typically use a specific criterion for a hot hand:
A player has a higher probability of success on the next attempt if he or she
has just succeeded than if he or she has just failed. Often written as:
p (success | past success) > p (success | past failure)
A previous success is thought to give player greater confidence, help him or
her maintain concentration, etc.
Shots After
1 HitH H H H H H H M H H M H M H H H M M
Actual
SequenceM M H H H H H H H H M H H H M M H H M H H H H M H M M
Shots After
1 MissM H H M H H H M
http://www.82games.com/kobe81.htm
Second Half Field-Goal Attempts (2 or 3 PT) of
Kobe Bryant’s 81-Point Game (January 22, 2006)
Conditional on Last Prior Attempt: p (hit|hit) = 13/18 = .72; p (hit|miss) = 5/8 = .63
Can also condition on hitting/missing last two attempts, last three attempts, etc.
Shots After
1 HitH H H H H H H M H H M H M H H H M M
Actual
SequenceM M H H H H H H H H M H H H M M H H M H H H H M H M M
Shots After
1 MissM H H M H H H M
No. of Hot Hand Studies Over the Years
Articles citing Gilovich et al. (1985) and containing an empirical
study of sports performance after success or failure. Bibliography
available through my website.
0
2
4
6
8
10
12
1985 1990 1995 2000 2005 2010 2015 2020
Let’s take a quiz at this point:
Pat, an established 37% shooter on three-pointers, makes
three in a row in a game. What would you expect Pat’s
shooting percentage on threes to be for Pat’s next few shots:
(a)A few percentage points lower than 37%
(b) Still 37%, give or take
(c)A few percentage points higher than 37%
(d)Several percentage points higher than 37%
How I’d have answered
a few years ago
How I’d answer now
Gilovich, Vallone, & Tversky (1985)
OVERALL
Limitations of Gilovich et al. (1985) Study of 76ers*
• Didn’t control for shot distances – player could shoot from
greater distance after hitting a few consecutive shots due to
overconfidence, which would work against hot streak.
• Didn’t control for how closely guarded a player was – player
who has hit a few consecutive shots could draw tighter
defense, again working against hot streak.
*The article contained two additional shooting studies, one with Celtics’ FT
data & the other involving a controlled shooting session with Cornell players.
NEWER STUDY TO ADDRESS SOME OF THESE ISSUES
Reading Between the Lines: How SportVU Cameras
Are Revolutionizing the NBA
https://www.slideshare.net/robbieloeb/rloeb-ppt-sportvuRobbie Loeb
BOCSKOCSKY ET AL. (2014)
https://www.bostonglobe.com/ideas/2014/02/09/the-hot-hand-might-real-after-
all/N8V34bGLWhPqk0Sx9yoHWI/story.html
[…John]
[…SKIP…]
BOSTON GLOBE
(2014)
LAST MONTH ON ESPN.COM (June 12, 2017),
CITES 2015 STUDY BY MILLER & SANJURJO
LET’S GO BACK TO 2015
Miller & Sanjurjo (2015)
Miller & Sanjurjo (2015) Analysis of NBA All-Star 3-PT Contests (With Correction to Overcome Systematic Understatement of Hot-Hand Effect)
Accuracy Gain
After 3 Straight
Hits (“Hotness”)
No. of
Contestants
.34 1
.20 to .22 3
.14 to .18 4
.11 to .12 5
.06 to .07 3
.05 2
.01 to .04 10
Negative 5
MEDIAN
16 players improved by
more than .05 (5%)
from their usual base
rate after hitting 3
straight
15 improved by less than
5% (or even did worse than
usual) after 3 straight hits
2017 (AFTER ESPN.COM ARTICLE)
Findings from Other Sports
• Summary from my 2011 book: “streakiness will occur most
readily with relatively simple motions (e.g., bowling, golf
putting) that can be repeated quickly, so that motor memories
of the action can be retained …” (p. 131)
• Selected developments post-2011
o 2016 study by Green & Zwiebel suggests (contrary to prior research) that
there may be streak-hitting in MLB game data (e.g., “the difference between
a recent on-base percentage of .100 and .500 (representing a recent cold run
and hot run respectively) translates to an increased probability of getting on
base of… 2.5%, or 25 OBP points”).
o In-depth case study of NFL’s Peyton Manning (Bullard, 2016): “Peyton was
actually less likely to complete a pass if he had a higher complex heat
[higher percentage of his last four passes completed than would be
statistically expected, factoring in difficulty of attempt].”
Outstanding Issues in Hot Hand Research
• Streaks that defy usual pattern of coming from top-
level athletes or teams
• Team dynamics (e.g., “contagion”) from one player to
another
• Baseball hitting streaks (at least one hit in consecutive games)
o Joe DiMaggio’s record 56-game hitting-streak in 1941 (compiled season-specific batting
averages between .323-.381 from 1936-1940);
o Wee Willie Keeler, second-longest hitting streak (45 games, 1896-97), batted .371 and .377
in the two prior seasons
o Pete Rose, third-longest streak (44, 1978), batted ≥ .300 in 12 of 13 seasons before streak.
• College basketball winning streaks
o John Wooden’s UCLA men’s basketball teams winning 88 straight games in the 1970s
(program had already won 6 NCAA titles before start of this streak)
o Geno Auriemma’s UConn women, separate win streaks of 111, 90, and 70 straight
(program had already won 2 NCAA titles before first of these streaks)
• Tiger Woods making the cut in 142 straight pro golf tournaments
Indeed, prominent streaks are usually amassed by athletes and teams who, even without their
respective streaks, would be considered among the finest practitioners of their sports
“Long streaks always are, and must be, a matter of extraordinary luck imposed upon great skill.”
– Stephen Jay Gould (1941-2002), Harvard paleontologist (and sometimes statistical writer)
16-game win streak
Prior 11-9 record After win streak, 23-23
(5 reg., 4 OT losses) (19 reg., 4 OT losses)
Previous season: 34-48 (40 reg., 8 OT losses)
Two play-off appearances in first 15 seasons (2000-01 to 2015-16; NHL lock-out 2004-05)
So Where Does a Streak Like This – in a Mediocre Team – Come From?
http://www.hockey-reference.com/
https://fivethirtyeight.com/features/scooter-gennett-is-somehow-not-
the-most-random-player-to-hit-four-hrs/
“[Scooter] Gennett [who hit 4 homers in a game on June 6, 2017] is the baseball
equivalent of Devin Booker scoring 70 points in an NBA game, or Nick
Foles tossing seven touchdown passes in the NFL. Part of why we watch sports
is that in any given game there’s the chance that a mediocre middle infielder
might explode for one of the best offensive performances ever.”
Five-Thirty-Eight on Other “Out of Nowhere” Hot Performances
Team Dynamics in Long Winning Streaks
http://seamheads.com/blog/2013/11/26/scalding-50-game-stretches-
in-mlb-history-and-how-teams-did-immediately-before-and-after/
The 2013 L.A. Dodgers had a 42-8 midseason stretch (June 22-August 17), tied
for the third-best 50-game sequence in MLB history (the two better ones occurred
in 1906 and 1912). The key was getting superior performances from many
players at once. Quoting from my own “Seamheads” article on the Dodgers’ run:
•Outfielder Yasiel Puig, whose June 3 Dodger debut predated the scald by a couple of weeks,
recorded OPS numbers of 1.180, .789, and .920, in June, July, and August, respectively.
• Shortstop Hanley Ramirez, who hardly played at all in April or May due to injury, put up OPS
values of 1.086 and 1.065 in June and July…
• Pitcher Zack Greinke, who missed action early… and then needed several starts to find his
groove, finally did so. In 16 starts from July 8 to the end of the regular season, Greinke allowed
more than 2 earned runs only once.
• Fellow starter Clayton Kershaw was similarly brilliant. In 16 starts in June, July, and August, he
allowed more than 2 earned runs twice.
• Reliever Kenley Jansen “completed a hidden perfect game…, setting down exactly 27 batters in
a row over 10 appearances from July 23 to August 8..” (ESPN/Grantland)
Hitting Is Contagious in Baseball: Evidence from Long Hitting Streaks•Joel R. Bock ,
•Akhilesh Maewal,
•David A. Gough
Figure 5. Mean BA versus relative lineup position.
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0051367
(Public Library of Science)
“Negative values
along the abscissa
correspond to
batting before the
streak hitter.”
Batting while teammate
currently has ≥ 30-game
hitting streak.
SHAMELESS PLUG (2011 BOOK)
