## 4142

Expand Messages
• 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
• Show all 3 messages in this topic