You Are Here > Basketball-Reference.com > BBR Blog > NBA and College Basketball Analysis

SITE NEWS: We are moving all of our site and company news into a single blog for Sports-Reference.com. We'll tag all Basketball-Reference content, so you can quickly and easily find the content you want.

Also, our existing Basketball-Reference blog rss feed will be redirected to the new site's feed.

Basketball-Reference.com // Sports Reference

For more from Neil, check out his new work at BasketballProspectus.com.

Likelihood of Recent Winning Streaks

Posted by Neil Paine on December 14, 2010

Although we're only a month and a half into the season, the 2010-11 campaign has already seen its share of impressive winning streaks. The Spurs rattled off 12 straight across almost the entire month of November (a streak matched by the Mavericks last week), the Lakers & Hornets each won 8 consecutive to start the year, and the Celtics, Heat, & Knicks are currently in the midst of 8+ game win streaks themselves. How probable have these runs of victories been?

To answer this question, I'm turning to SPM in much the same way I did in this post. In a nutshell, I ran SPM for every player this season, but forced the team weighted sum to equal an efficiency differential that had been regressed to the mean with 908 possessions of league-average play. This allows us to use a full-season logistic win probability model to predict the outcome of any game:

p(home W) ~ 1 / (1 + exp(-0.525 - 0.15*Diff))

Where "Diff" is the home team's efficiency differential minus the road team's efficiency differential. Using this formula, each team's 2010-11 regressed SPM scores, and the distribution of minutes to each player in the game, I was able to generate the probability of each team winning each game this season, which in turn allowed me to calculate the likelihood of each winning streak.

Here are the probabilities, from most likely to least likely:

LA Lakers - 8 straight from 10/26 to 11/09 (20.6%)

Date Tm Opp tmRtg opRtg ishome p(W)
10/26/2010 LAL HOU 6.11 3.04 1 72.8%
10/29/2010 LAL PHO 7.20 -2.72 0 72.4%
10/31/2010 LAL GSW 2.69 -13.39 1 95.0%
11/2/2010 LAL MEM 2.73 -5.48 1 85.3%
11/3/2010 LAL SAC 7.50 -4.45 0 78.0%
11/5/2010 LAL TOR 7.37 -2.07 1 87.4%
11/7/2010 LAL POR 1.70 -4.04 1 80.0%
11/9/2010 LAL MIN 3.43 -6.58 1 88.4%
8-gm W streak 20.6%

Miami - 9 straight from 11/29 to 12/13 (11.2%)

Date Tm Opp tmRtg opRtg ishome p(W)
11/29/2010 MIA WAS 7.48 -6.53 1 93.2%
12/1/2010 MIA DET 3.73 -6.92 1 89.3%
12/2/2010 MIA CLE 5.00 -8.56 0 81.9%
12/4/2010 MIA ATL 8.71 0.67 1 84.9%
12/6/2010 MIA MIL 8.15 -1.86 0 72.7%
12/8/2010 MIA UTA 9.82 6.22 0 50.4%
12/10/2010 MIA GSW 7.00 -12.46 0 91.6%
12/11/2010 MIA SAC 8.11 -2.85 0 75.4%
12/13/2010 MIA NOH 9.11 4.65 1 76.7%
9-gm W streak 11.2%

New York - 8 straight from 11/28 to 12/12 (6.8%)

Date Tm Opp tmRtg opRtg ishome p(W)
11/28/2010 NYK DET 1.24 -4.02 0 56.6%
11/30/2010 NYK NJN 2.93 -5.79 1 86.2%
12/3/2010 NYK NOH 5.06 -5.61 0 74.5%
12/5/2010 NYK TOR 4.41 1.04 0 49.5%
12/6/2010 NYK MIN 4.81 -2.04 1 82.5%
12/8/2010 NYK TOR 6.71 -3.15 1 88.1%
12/10/2010 NYK WAS 5.90 -3.14 0 69.7%
12/12/2010 NYK DEN 6.29 2.64 1 74.5%
8-gm W streak 6.8%

Boston - 10 straight from 11/22 to 12/11 (3.4%)

Date Tm Opp tmRtg opRtg ishome p(W)
11/22/2010 BOS ATL -0.34 -4.02 0 50.7%
11/24/2010 BOS NJN 6.79 -1.22 1 84.9%
11/26/2010 BOS TOR 10.97 3.07 1 84.7%
11/30/2010 BOS CLE 7.74 -6.71 0 83.8%
12/1/2010 BOS POR 12.50 0.68 1 90.9%
12/3/2010 BOS CHI 8.68 4.51 1 76.0%
12/5/2010 BOS NJN -3.92 -9.07 0 56.1%
12/8/2010 BOS DEN 7.75 0.52 1 83.3%
12/9/2010 BOS PHI 8.88 4.58 0 53.0%
12/11/2010 BOS CHA 1.00 -6.60 0 64.9%
10-gm W streak 3.4%

San Antonio - 12 straight from 11/1 to 11/24 (2.8%)

Date Tm Opp tmRtg opRtg ishome p(W)
11/1/2010 SAS LAC 2.46 -5.64 0 66.6%
11/3/2010 SAS PHO 3.46 -1.01 0 53.6%
11/6/2010 SAS HOU 8.71 -4.47 1 92.4%
11/8/2010 SAS CHA 8.44 -4.42 0 80.3%
11/10/2010 SAS LAC 8.42 -8.35 1 95.4%
11/13/2010 SAS PHI 0.73 -4.12 1 77.7%
11/14/2010 SAS OKC 7.62 1.84 0 58.5%
11/17/2010 SAS CHI 9.67 2.03 1 84.2%
11/19/2010 SAS UTA 10.15 4.77 0 57.0%
11/20/2010 SAS CLE 7.08 -6.52 1 92.9%
11/22/2010 SAS ORL 9.10 4.94 1 75.9%
11/24/2010 SAS MIN 7.95 -1.77 0 71.7%
12-gm W streak 2.8%

Dallas - 12 straight from 11/20 to 12/11 (0.3%)

Date Tm Opp tmRtg opRtg ishome p(W)
11/20/2010 DAL ATL 5.56 3.65 0 44.1%
11/23/2010 DAL DET 6.49 -5.76 1 91.4%
11/24/2010 DAL OKC 7.35 1.98 0 57.0%
11/26/2010 DAL SAS 8.13 9.35 0 33.0%
11/27/2010 DAL MIA 6.99 7.90 1 59.6%
11/29/2010 DAL HOU -0.18 -2.71 1 71.2%
12/1/2010 DAL MIN 1.71 -4.64 1 81.4%
12/3/2010 DAL UTA 2.71 3.55 0 34.3%
12/4/2010 DAL SAC 4.32 -3.81 0 66.7%
12/7/2010 DAL GSW 3.38 -2.47 1 80.3%
12/9/2010 DAL NJN 3.47 -6.89 1 88.9%
12/11/2010 DAL UTA 5.62 4.41 1 67.0%
12-gm W streak 0.3%

New Orleans - 8 straight from 10/27 to 11/13 (0.1%)

Date Tm Opp tmRtg opRtg ishome p(W)
10/27/2010 NOH MIL 2.95 2.60 1 64.1%
10/29/2010 NOH DEN 3.03 2.48 1 64.7%
10/30/2010 NOH SAS -3.58 9.43 0 7.8%
11/3/2010 NOH HOU -0.41 -0.27 0 36.7%
11/5/2010 NOH MIA 1.62 10.35 1 31.3%
11/6/2010 NOH MIL 1.02 -0.37 0 42.1%
11/9/2010 NOH LAC -2.57 -9.90 1 83.5%
11/13/2010 NOH POR 0.91 -2.92 1 75.0%
8-gm W streak 0.1%

Here were the distributions of minutes from that Hornets-Spurs game where New Orleans had less than an 8% chance of winning:

Date Player Tm Opp GS MP SPM tmRtg ishome p(W)
10/30/2010 Chris Paul NOH SAS 1 31.1 12.84 -3.58 0 7.8%
10/30/2010 Trevor Ariza NOH SAS 1 31.1 0.52 -3.58 0 7.8%
10/30/2010 Marcus Thornton NOH SAS 0 30.5 -6.28 -3.58 0 7.8%
10/30/2010 David West NOH SAS 1 25.7 3.51 -3.58 0 7.8%
10/30/2010 Willie Green NOH SAS 0 23.4 -5.22 -3.58 0 7.8%
10/30/2010 Marco Belinelli NOH SAS 1 22.8 -2.33 -3.58 0 7.8%
10/30/2010 Jason Smith NOH SAS 0 20.8 -4.03 -3.58 0 7.8%
10/30/2010 Emeka Okafor NOH SAS 1 18.6 -1.31 -3.58 0 7.8%
10/30/2010 Didier Ilunga-Mbenga NOH SAS 0 15.3 -4.79 -3.58 0 7.8%
10/30/2010 Jerryd Bayless NOH SAS 0 11.3 -7.61 -3.58 0 7.8%
10/30/2010 Pops Mensah-Bonsu NOH SAS 0 9.6 -4.58 -3.58 0 7.8%
10/30/2010 DeJuan Blair SAS NOH 1 38.3 1.83 9.43 1 92.2%
10/30/2010 Manu Ginobili SAS NOH 1 36.9 7.73 9.43 1 92.2%
10/30/2010 Richard Jefferson SAS NOH 1 33.4 1.25 9.43 1 92.2%
10/30/2010 Tim Duncan SAS NOH 1 27.5 1.53 9.43 1 92.2%
10/30/2010 Tony Parker SAS NOH 1 26.9 3.20 9.43 1 92.2%
10/30/2010 George Hill SAS NOH 0 26.5 1.81 9.43 1 92.2%
10/30/2010 Antonio McDyess SAS NOH 0 21.2 -3.50 9.43 1 92.2%
10/30/2010 Gary Neal SAS NOH 0 18.8 -1.54 9.43 1 92.2%
10/30/2010 James Anderson SAS NOH 0 10.6 -1.62 9.43 1 92.2%

If we regressed to preseason projections instead of the league average, New Orleans' expected win % would probably be higher... but still, they went into San Antonio, played Chris Paul & David West less than their usual MPG, gave significant minutes to Marcus Thornton, Willie Green, & Jason Smith (all of whom have been varying degrees of terrible this season) and still came away with the victory, paving the way for the most unlikely long winning streak of the season so far.

ShareThis

6 Responses to “Likelihood of Recent Winning Streaks”

  1. Nathan Walker Says:

    Neil,

    This is very interesting stuff! What software do you use to make logistic regression?

    -Nathan

  2. Neil Paine Says:

    I use R, which is free and (for my purposes) can do pretty much anything a high-priced package does.

    http://www.r-project.org/

  3. Gil Meriken Says:

    Q:What do pirates use for statistical computing?

    A: ARRRRRR

  4. Neil Paine Says:

    Nice. That one definitely couldn't wait until September 19.

  5. DSMok1 Says:

    Notes on the distribution of minutes in that NO-SAS game: of course, the reason West and Paul played so little is that they were way ahead. The distribution would have been different had the game been closer.

    I'm not sure how to account for that.

  6. Neil Paine Says:

    I don't think you can. But theoretically, playing Marcus Thornton, Willie Green, & Jason Smith so much could have made it a close game again (and in fact, San Antonio outscored them 30-23 in the 4th).