The Impact of Power Plays in The Impact of Power Plays in NHL Hockey, or: NHL Hockey, or: No Dogs No Dogs

Play HockeyPlay Hockey

Jordan Pedersen, Tom Geiger, Jordan Pedersen, Tom Geiger, and Waleed Khouryand Waleed Khoury

Some BackgroundSome Background A team is said to be on a A team is said to be on a

power play when at least power play when at least one opposing player is one opposing player is serving a penalty ANDserving a penalty AND

The team has a The team has a numerical advantage on numerical advantage on the icethe ice

Whenever both teams Whenever both teams have the same number have the same number of penalties being of penalties being served, there is no served, there is no power playpower play

MethodologyMethodology Using League Data for Using League Data for

this season and the this season and the preceding four preceding four seasonsseasons

Focusing on Rankings Focusing on Rankings (based on points) and (based on points) and power play conversion power play conversion percentagespercentages

Regular SeasonRegular Season

Refresher on 2-Sample T Refresher on 2-Sample T TestTest

Used to analyze whether the difference in means Used to analyze whether the difference in means between two independent groups of data is between two independent groups of data is statistically significantstatistically significant

1-sample t-tests are for measuring the difference in 1-sample t-tests are for measuring the difference in mean for a single group versus a hypothesized meanmean for a single group versus a hypothesized mean

Use of the TestUse of the Test Test will be used to see if there is a Test will be used to see if there is a

statistically significant difference between statistically significant difference between power play conversion percentages for top power play conversion percentages for top 15 teams vs. bottom 15 teams (based on 15 teams vs. bottom 15 teams (based on their their PointPoint total) total)

Therefore, our question is…Therefore, our question is… Does the ability to convert power plays Does the ability to convert power plays

really affect a team’s ability to win games?really affect a team’s ability to win games?

Current SeasonCurrent Season Open up PP%Top and Bottom.mtwOpen up PP%Top and Bottom.mtw We’ll be doing 2008-2009We’ll be doing 2008-2009

A surpriiiiithe?A surpriiiiithe?

Mandatory Class ExerciseMandatory Class Exercise ¼ of the class does 2007-2008¼ of the class does 2007-2008 ¼ does 2006-2007¼ does 2006-2007 ¼ does 2005-2006¼ does 2005-200611

¼ does 2003-2004¼ does 2003-2004

1: Ties and dogs were banned after the 2004-2005 lockout1: Ties and dogs were banned after the 2004-2005 lockout

Relationship between Points Relationship between Points (Not Goals) and PP%(Not Goals) and PP%

Linear Regression ModelLinear Regression Model Remember, a team is awarded 2 Remember, a team is awarded 2

points if they win, 1 point if they lose points if they win, 1 point if they lose in OT/shootout, and 0 points if they in OT/shootout, and 0 points if they lose in regulationlose in regulation

2008-20092008-2009

PP%

P

2624222018161412

110

100

90

80

70

60

50

S 10.9875R-Sq 25.6%R-Sq(adj) 22.9%

Fitted Line PlotP = 44.03 + 1.975 PP%

2007-20082007-2008

PP%

P

25.022.520.017.515.0

120

110

100

90

80

70

S 9.68195R-Sq 16.8%R-Sq(adj) 13.9%

Fitted Line PlotP = 57.51 + 1.896 PP%

2006-20072006-2007

PP%

P

24222018161412

120

110

100

90

80

70

60

50

S 13.6885R-Sq 30.6%R-Sq(adj) 28.1%

Fitted Line PlotP = 32.40 + 3.356 PP%

2005-20062005-2006

PP%

P

222018161412

130

120

110

100

90

80

70

60

50

S 12.4745R-Sq 44.9%R-Sq(adj) 43.0%

Fitted Line PlotP = 6.66 + 4.802 PP%

2003-20042003-2004

PP%

P

22201816141210

110

100

90

80

70

60

S 14.9092R-Sq 12.5%R-Sq(adj) 9.4%

Fitted Line PlotP = 50.53 + 2.204 PP%

A Note on Our FailureA Note on Our Failure We tried to compare shooting We tried to compare shooting

percentages on and off a power play, percentages on and off a power play, but the NHL is skimpy (unhelpful) but the NHL is skimpy (unhelpful) when it comes to datawhen it comes to data

Shots on goal during power plays Shots on goal during power plays were unavailablewere unavailable

ConclusionsConclusions In In generalgeneral, better teams , better teams

tend to be better at tend to be better at converting power playsconverting power plays

But a direct correlation But a direct correlation was not to be foundwas not to be found

More sophisticated data More sophisticated data is needed from the is needed from the leagueleague

We attribute this lack of We attribute this lack of data to lack of dogs in data to lack of dogs in the NHLthe NHL

CitationsCitations http://en.wikipedia.org/wiki/Power_pl

ay_(sport) Tommy, AJ, and Catherine’s Tommy, AJ, and Catherine’s

Presentation (for definition of 2-Presentation (for definition of 2-sample t tests)sample t tests)

Food For Thought…Food For Thought…

Why is this dog smoking Why is this dog smoking andand playing hockey? playing hockey? What statistical model would most accurately What statistical model would most accurately

predict this behavior?predict this behavior?