NAME:  NFL Scores and Pointspreads
TYPE:  Census (All values from recent seasons) 
SIZE:  235 or 251 observations, 8 variables

DESCRIPTIVE ABSTRACT:
Four datasets (nfl93.dat, nfl94.dat, nfl95.dat, nfl96.dat) contain
National Football League game results for recent seasons.  In addition
to game scores, the datasets give oddsmakers' pointspreads and
over/under values for each game.

SOURCE:
The data were taken from _The Gold Sheet_ (http://www.goldsheet.com).

VARIABLE DESCRIPTIONS:
Columns 
 1 -  9  Date of game
11 - 24  Visiting team name
26 - 27  Visiting team score
30 - 43  Home team name
45 - 46  Home team score
49 - 49  Indicator for overtime games (o or -)
51 - 56  Pointspread (see story for explanation)
61 - 64  Over/Under  (see story for explanation)

Values are aligned and delimited by blanks.

SPECIAL NOTES:
The teams are the same each year with the following exceptions:

LA Raiders became Oakland in 1995.
LA Rams became St. Louis in 1995.
Carolina and Jacksonville were new teams added in 1995.
Cleveland became Baltimore in 1996.

The last game in each dataset is the Super Bowl, which is played at a
neutral site.

STORY BEHIND THE DATA:
The datasets contain scores from the 1993-96 NFL seasons.  Before each
week's games, the oddsmakers (in the case of our data, _The Gold
Sheet_) attempt to forecast the margin of victory for each game.  These
predictions are known as the pointspreads.  Their intent is to equalize
two competing teams by setting an amount to add to (or subtract from)
one team's score before determining the "winner against the spread."
In these datasets, the pointspread adjustments are made to the home
team's score.  Thus a pointspread of -6.5 indicates that the home team
is favored by 6.5 points.  A bettor who chooses the favored home team
will only win if the home team wins by 7 or more points; a victory by
the visitor or a loss by 6 or fewer points means the bettor loses.  In
reality, the oddsmaker's goal is to set the pointspread on any given
game so that equal amounts are wagered both for and against the favored
team.

A similar philosophy drives the over/under value, which is compared to
the total points scored by both teams.  Again the bettor may choose to
wager on whether the two teams will combine to score more (over) or
fewer (under) points than the over/under line.

Additional information about these data can be found in the "Datasets
and Stories" article "NFL Scores and Pointspreads" in the _Journal of
Statistics Education_ (Lock 1997).  

PEDAGOGICAL NOTES:
The NFL scores alone can be used to investigate a variety of questions
of interest to sports-minded students.  What are typical NFL scores and
margins of victory?  Is there a home field advantage, and, if so, how
can it be quantified?  Can we predict future game scores from past game
results?  The additional betting information suggests easily motivated
questions about the accuracy of the pointspreads and over/under
values.  Students can also create and check various betting strategies
(e.g., always choose a home underdog when the visitor is favored by
more than four points).  The separate files for each season allow
models to be fit for data from one season and then tested on data from
another season.

REFERENCES:
_The Gold Sheet_, http://www.goldsheet.com

National Sports Services, Inc., _Introduction To Las Vegas
Sports Betting_, http://www.nss.net/Gazette/Intro.html

SUBMITTED BY:
Robin H. Lock
Mathematics Department
St. Lawrence University
Canton, NY  13617
rlock@vm.stlawu.edu