Sports Reference Blog
Stat Questions: Why Do Pre-1970s Team Rebound Totals Not Match the Sums of Individual Players?
Posted by Neil on October 15, 2013
Recently, a BBR user posed a question we get on occasion:
"[I] noticed that the team rebound totals for every team appear to be incorrect from 1956-57 to 1967-68. They are correct in 1968-69. For example in 1956-57 it shows the Celtics led the league in rebounds with 4963. When you add up the rebounds for every player on their roster the total comes to 4578. The points and assists totals match exactly. [...] It is only the rebound total that is off, and it is off for every team by a significant margin."
He's right -- you can see this by adding up the team rebound totals for each league-season and comparing it to the sum of individual player rebounds... It changes around 1968:
+---------+-------+----------+------------+ | year_id | lg_id | team_trb | player_trb | +---------+-------+----------+------------+ | 2013 | NBA | 103575 | 103575 | | 2012 | NBA | 83513 | 83513 | | 2011 | NBA | 101816 | 101816 | | 2010 | NBA | 102640 | 102640 | | 2009 | NBA | 101586 | 101586 | | 2008 | NBA | 103271 | 103271 | | 2007 | NBA | 100994 | 100994 | | 2006 | NBA | 100754 | 100754 | | 2005 | NBA | 102970 | 102970 | | 2004 | NBA | 100361 | 100361 | | 2003 | NBA | 100604 | 100604 | | 2002 | NBA | 100829 | 100829 | | 2001 | NBA | 100988 | 100988 | | 2000 | NBA | 102062 | 102062 | | 1999 | NBA | 60395 | 60395 | | 1998 | NBA | 98798 | 98798 | | 1997 | NBA | 97703 | 97703 | | 1996 | NBA | 98099 | 98099 | | 1995 | NBA | 92006 | 92006 | | 1994 | NBA | 95192 | 95192 | | 1993 | NBA | 95504 | 95504 | | 1992 | NBA | 96680 | 96680 | | 1991 | NBA | 95776 | 95776 | | 1990 | NBA | 95518 | 95518 | | 1989 | NBA | 90031 | 90031 | | 1988 | NBA | 81828 | 81828 | | 1987 | NBA | 83020 | 83020 | | 1986 | NBA | 82161 | 82161 | | 1985 | NBA | 82008 | 82008 | | 1984 | NBA | 81150 | 81150 | | 1983 | NBA | 83853 | 83853 | | 1982 | NBA | 81987 | 81987 | | 1981 | NBA | 82010 | 82010 | | 1980 | NBA | 81065 | 81065 | | 1979 | NBA | 81564 | 81564 | | 1978 | NBA | 84984 | 84984 | | 1977 | NBA | 84886 | 84886 | | 1976 | NBA | 69960 | 69960 | | 1976 | ABA | 30815 | 30815 | | 1975 | NBA | 69468 | 69468 | | 1975 | ABA | 40239 | 40239 | | 1974 | NBA | 67230 | 67230 | | 1974 | ABA | 40705 | 40705 | | 1973 | NBA | 70555 | 70555 | | 1973 | ABA | 41062 | 41062 | | 1972 | NBA | 71299 | 71299 | | 1972 | ABA | 48429 | 48429 | | 1971 | NBA | 74059 | 74059 | | 1971 | ABA | 50234 | 50234 | | 1970 | NBA | 60697 | 60697 | | 1970 | ABA | 49991 | 49991 | | 1969 | NBA | 65324 | 65324 | | 1969 | ABA | 46674 | 46674 | | 1968 | NBA | 65166 | 56999 | | 1968 | ABA | 46957 | 46957 | | 1967 | NBA | 54536 | 48095 | | 1966 | NBA | 49118 | 43250 | | 1965 | NBA | 48433 | 42563 | | 1964 | NBA | 47423 | 41894 | | 1963 | NBA | 48044 | 41418 | | 1962 | NBA | 51415 | 43183 | | 1961 | NBA | 46314 | 40732 | | 1960 | NBA | 44104 | 37401 | | 1959 | NBA | 40343 | 34794 | | 1958 | NBA | 41279 | 35814 | | 1957 | NBA | 35948 | 32136 | | 1956 | NBA | 34616 | 31395 | | 1955 | NBA | 32292 | 28777 | | 1954 | NBA | 32987 | 29808 | | 1953 | NBA | 36168 | 32314 | | 1952 | NBA | 35977 | 31209 | | 1951 | NBA | 35019 | 30621 | +---------+-------+----------+------------+
So what's the deal? Is this a bug in our database?
Actually, no. It's just a matter of accounting by the official scorer, because technically speaking, for every missed shot there has to be a rebound.
Starting in 1968-69 (1967-68 in the ABA), so-called "team" rebounds (rebounds where there was no clear individual who should receive credit) were no longer counted toward a team's overall rebounding total. Before that, "team rebounds" were credited at the team level, but they (obviously) didn't make it into individual rebounding totals. This is what caused the massive discrepancies between teams' rebounds and the sum of their individual players' rebounds.
Nowadays, those "team rebounds" are thrown into their own bucket, neither allocated to individuals nor to teams for the purpose of overall stat totals.
Mystery solved!
[…] This probably doesn't make a great deal of sense in 2013, but it does come in handy for years before QB sack data was tracked (a.k.a. the history of football up until 1969). Because of this practice, we know how many gross yards a quarterback -- and, therefore, a team -- had, as well as how many net yards they had, since sack totals were recorded for teams (but not players) before 1969. It would make for even more confusion if, starting in 1969, we all of a sudden began defining yardage for individuals differently than it had been defined in the past (though as we saw yesterday, this didn't stop the NBA from abruptly changing how team rebound totals were defined). […]