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  • igor eduardo küpfer
    May 30, 2004
      Whoa! Lotta traffic at apbr_*. To add to the bustle, I post the following,
      an unfinished study of mine on the effects of team travel on winning.

      ***

      What are the factors in travel that affect team performance? To begin to
      answer this question, I regressed the results of the 2000-01 season against
      four variables:

      Days - Number of days between games, eg back to back games = 1
      Dist - Distance in miles from location of previous game to next
      game.[1]
      Home - Home court dummy, home court = 1 away game = 0
      MatchupP - Probability of team winning game [2]

      I used the points differential for each game as the response.

      I made the following assumption: that teams never return home between road
      games; that is, if the Spurs played in Seattle just before the All-Star
      break, and played in Miami just following the break, I used the travel
      distance between Seattle and Miami, even though the Spurs likely went back
      to San Antonio between games. Also, to remove the ambiguity of the amount of
      rest at the beginning of the season, I removed each team's first game of the
      season from my sample.

      The results show that only the Matchup Probability and Home/Away variables
      are significant at 5%. (Regression results appended to end of this post.)
      The Days Between Games variable is not significant (p = 0.121) but I think
      that may be an artefact of my sample, because I've seen other study which
      show a significant relationship.

      ***

      [1 Distance approximated using the following method:

      Distance between cities = sqrt(x * x + y * y)

      where x = 69.1 * (lat2 - lat1)
      and y = 69.1 * (lon2 - lon1) * cos(lat1/57.3) ]

      [2 Probability of team win calculated using Bill James's log5 method:

      Pr(team win) = (A - A * B) / (A + B - 2 * A * B)

      where A and B = team A's and team B's winning percentage, respectively. For
      this study, I used Pythagorean winning percentages instead.]


      REGRESSION OUTPUT

      The regression equation is
      PtsDiff = - 18.7 + 0.391 Days +0.000051 Dist + 5.76 Home + 29.9 MatchupP

      Predictor Coef SE Coef T P
      Constant -18.6980 0.8449 -22.13 0.000
      Days 0.3908 0.2518 1.55 0.121
      Dist 0.0000513 0.0003559 0.14 0.886
      Home 5.7589 0.4832 11.92 0.000
      MatchupP 29.914 1.135 26.35 0.000

      S = 11.11 R-Sq = 26.9% R-Sq(adj) = 26.7%

      Analysis of Variance

      Source DF SS MS F P
      Regression 4 106275 26569 215.13 0.000
      Residual Error 2344 289491 124
      Lack of Fit 2239 278271 124 1.16 0.158
      Pure Error 105 11220 107
      Total 2348 395767

      2139 rows with no replicates

      --

      ed
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