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1743Height impacts

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  • Dean Oliver
    Feb 1, 2003

      First of all, here are average heights (weighted by minutes played) of teams through time:

       

      SeasonYear

      AvgOfMinWtdHt

      DiffPvsYr

      1952

      76.2

       

      1953

      76.4

      0.1

      1954

      76.6

      0.2

      1955

      76.7

      0.2

      1956

      77.1

      0.3

      1957

      77.2

      0.2

      1958

      77.3

      0.0

      1959

      77.2

      0.0

      1960

      77.4

      0.2

      1961

      77.5

      0.1

      1962

      77.5

      0.0

      1963

      77.6

      0.1

      1964

      77.7

      0.1

      1965

      77.8

      0.1

      1966

      77.6

      -0.2

      1967

      77.6

      0.0

      1968

      77.8

      0.2

      1969

      77.9

      0.1

      1970

      77.8

      -0.1

      1971

      77.9

      0.1

      1972

      77.9

      0.0

      1973

      77.9

      0.1

      1974

      77.9

      0.0

      1975

      78.0

      0.1

      1976

      78.2

      0.1

      1977

      78.2

      0.0

      1978

      78.3

      0.1

      1979

      78.3

      0.0

      1980

      78.4

      0.1

      1981

      78.6

      0.2

      1982

      78.7

      0.1

      1983

      78.7

      0.0

      1984

      78.8

      0.1

      1985

      78.9

      0.1

      1986

      79.1

      0.2

      1987

      79.3

      0.2

      1988

      79.3

      0.0

      1989

      79.0

      -0.2

      1990

      78.9

      -0.1

      1991

      79.0

      0.1

      1992

      78.8

      -0.2

      1993

      78.8

      0.0

      1994

      78.9

      0.0

      1995

      79.1

      0.2

      1996

      79.1

      0.0

      1997

      78.9

      -0.2

      1998

      78.9

      -0.1

      1999

      78.9

      0.0

      2000

      78.9

      0.0

      2001

      78.9

      -0.1

       

      (I don’t remember how to post tables so they format right, so I may try this a couple times.)

       

      A long trend of increasing heights (posted in part to compare to MSG’s stuff).  Decreases in average height seem to be the year of or the year after expansion.  Teams are definitely more than an inch taller now than in the ‘60’s.  There does appear to be a correlation between league average height and league average points scored per possession (about 80%).  I ran some experiments within seasons to look at the increment better than the league average points per possessions (offense and defense) as a function of increment above the league average height and I get very statistical significant results (>99.9% significant).  Offensively teams show an improvement of 0.78 pts per 100 possessions for each inch over the league average in height.  Defensively, it’s about 0.57.  However, this by no means explains the full increase in league average points per possessions that has occurred since 1974.  The ABA merger and the 3pt shot both had effects, though the ABA merger perhaps had more of an effect.

       

      I want to do some work to extract what this means on an individual basis – if an inch of height teamwise implies 1.35 pts/100 poss improvement, does it mean the same for individuals?  Maybe, if applied right.  I don’t think it means that a 7 footer is 13.5 pts/100 possessions better than a guy 6’2”.  But a 7’ power forward may be an average of about 4 pts/100 poss better than a 6’9” power forward.  Decisions by basketball people have not been made on pts/100 poss basis.  I’d like to understand whether I can make that correlation to see if they have over- or under-estimated the impact of height.  My gut says that they’ve overestimated that impact.

       

      I also need to think about other ways to identify these team numbers that may be better.

       

      (MikeG – did you notice that your minutes played ratio is over 1 in 1995 before expansion and less than 1 in 1996, the year of expansion?)

       

      Dean Oliver

      deano@...

      Journal of Basketball Studies

      http://www.rawbw.com/~deano/

      6052 Chabot Rd. #9

      Oakland, CA 94618

      (510) 655-4087

       

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