NAME: Pay for Play: Are Baseball Salaries Based on Performance?
TYPE: Census (see descriptive abstract below)
SIZE: 337 observations, 18 variables
DESCRIPTIVE ABSTRACT:
We consider as our population of interest the set of Major League
Baseball players who played at least one game in both the 1991 and 1992
seasons, excluding pitchers. This dataset contains the 1992 salaries
for that population, along with performance measures for each player
from 1991. Four categorical variables indicate how free each player
was to move to other teams.
SOURCES:
CNN/Sports Illustrated at
http://www.cnnsi.com/baseball/mlb/historical_profiles/
_Sacramento Bee_, 10/15/91.
_The New York Times_, 11/13/91, 2/23/92, 11/19/92.
The Society for American Baseball Research (SABR) at
ftp://skypoint.com/pub/members/a/ashbury/sabr/SALARIES
/1992_salaries_baseball
VARIABLE DESCRIPTIONS:
Columns
1 - 4 Salary (in thousands of dollars)
6 - 10 Batting average
12 - 16 On-base percentage (OBP)
18 - 20 Number of runs
22 - 24 Number of hits
26 - 27 Number of doubles
29 - 30 Number of triples
32 - 33 Number of home runs
35 - 37 Number of runs batted in (RBI)
39 - 41 Number of walks
43 - 45 Number of strike-outs
47 - 48 Number of stolen bases
50 - 51 Number of errors
53 Indicator of "free agency eligibility"
55 Indicator of "free agent in 1991/2"
57 Indicator of "arbitration eligibility"
59 Indicator of "arbitration in 1991/2"
61 - 79 Player's name (in quotation marks)
SPECIAL NOTES:
Players' batting averages are calculated as the ratio of number of hits
to the number of hits plus the number of outs. On-base percentage is
the ratio of number of hits plus the number of walks to the number of
hits plus the number of walks plus the number of outs. A batting
average above .300 is very good; OBP above .400 is excellent. An RBI
is obtained when a runner scores as a direct result of a player's
at-bat.
I believe that number of hits serves as a proxy for the amount of
playing individuals did in the year. There is a statistic for number
of games played available, but this statistic counts any entry into the
game, even defensive participation for a single out, the same as
participating for the entire contest.
STORY BEHIND THE DATA:
Baseball provides a rare opportunity to judge the value of an employee
-- in this case, a player -- by standardized measures of performance.
The question is, what are those characteristics worth? In addition,
the economic principle of freedom of movement for employees can be
measured; that is, what financial benefit does a person gain if he is
able to change employers? Additionally, baseball fans may use their
analysis of this dataset, in combination with other similar datasets,
to gain insight into the salary structure in Major League Baseball.
Additional information about these data can be found in the "Datasets
and Stories" article "Pay for Play: Are Baseball Salaries Based on
Performance?" in the _Journal of Statistics Education_ (Watnik 1998).
PEDAGOGICAL NOTES:
This dataset can be useful during a regression course using a text such
as Neter, Kutner, Nachtsheim, and Wasserman (1996) or Christensen
(1996). The data require a transformation of the response variable and
detection and elimination of outliers. In addition, numerous model
building techniques may be employed. Students interested in baseball
will note the nice interpretations of some of the coefficients,
especially the fact that some models point to the newest free agents'
being paid less than in previous years, and the players' union winning
a grievance over that issue.
For more advanced students, the instructor may choose to discuss the
interpretation of estimated parameters in models where a
log-transformation (for example) is employed. In addition, with the
large number of explanatory variables, making future predictions is a
difficult issue.
REFERENCES:
Christensen, R. (1996), _Analysis of Variance, Design and Regression:
Applied Statistical Methods_, New York: Chapman and Hall.
Neter, J., Kutner, M. H., Nachtsheim, C. J., and Wasserman, W. (1996),
_Applied Linear Statistical Models_ (4th ed.), Chicago: Irwin.
SUBMITTED BY:
Mitchell R. Watnik
Department of Mathematics and Statistics
University of Missouri-Rolla
Rolla, MO 65409-0020
mwatnik@umr.edu