Methods and Definitions

Adjusted Field Goal Percent: An adjustment made to field goal percentage giving three-halves credit for three point shots made.

Adj FG%= (Total FG+0.5*3ptFG)/Total FGA

Approximate Value: An integer estimate of a player's value, making no fine distinctions, but, rather, distinguishing easily between very good seasons, average seasons, and poor seasons. There are two ways to calculate approximate value.

1. From Martin Manley:

Credits= PTS+REB+AST+STL+BLK-FGMISSED-FTMISSED-TO

Before the '73-74 season, steals, blocks, and turnovers weren't kept as official stats. In this formula, those stats are just omitted as they tend to cancel each other out to some degree when included anyway.


AV= Credits^(3/4)/21

If a player makes first team or second team All-Defense, then one point is added to his AV.

2. Points shall be assigned according to the following rules:

1. If a player plays in five games, he gets 1 point. If he plays in 25 games, he gets 2 points. 50 games, 3 points. 65 games, 4 points.

2. If a player's FG% is greater than 1.07 times the league FG%, then he gets 1 point. If a player's FG% is less than 0.97 times the league FG%, then subtract 1 point.

3. Assign AV points for total points scored with the following table:

0.5 points for 205 total points scored

1 for 410. 1.5 for 510. 2 for 615. 3 for 820.

3.5 for 1025. 4 for 1230. 4.5 for 1435. 5 for 1640.

6 for 2050. 6.5 for 2255. 7 for 2460. 7.5 for 2665.

8 for 2870. 8.5 for 3075. Etc.

4. Assign AV points for rebounds with the following table:

0.5 points for 100 rebounds.

1 for 200. 1.5 for 300. 2 for 400. 2.5 for 500.

3 for 600. 3.5 for 700. 4 for 800. 4.5 for 1000.

5 for 1200. 5.5 for 1400. 6 for 1600. 6.5 for 1800.

7 for 2000.

5. Assign AV points for assists using the following table:

0.5 points for 80 assists.

1 for 140. 1.5 for 200. 2 for 250. 2.5 for 300.

3 for 350. 3.5 for 450. 4 for 550. 4.5 for 650.

5 for 750. 5.5 for 850. 6 for 950. 6.5 for 1050.

7 for 1150.

6. 0.5 points for 50 steals. 1 for 100. 1.5 for 150. 2 for 200. 2.5 for 250.

7. 0.5 points for 40 blocks. 1 for 80. 1.5 for 120. 2 for 160. 2.5 for 200. 3 for 240. 3.5 for 300. 4 for 380.

8. Award one point for first or second team All-Defense.

9. If above the league average in 3-point FG%, then award 0.5 points if 3-pointers made is at least 0.4 times games played by the player. Award 1 point if the player made at least one three pointer per game and was above the league average in 3-point FG%.

10. Add all points acquired in rules 1 through 9, then multiply by 0.85 to get Approximate Value.

Floor Percent: Scoring possessions divided by possessions. The percentage of a team's possessions on which it scored at least one point. Floor % is well approximated for teams by the formula

Floor %= (FG+OR)/(FGA+TO)

Individual Floor %: A player's scoring possessions divided by his total possessions. A player's scoring possessions would be his field goals that weren't assisted on, plus a certain percentage of his field goals that were assisted on, plus a certain percentage of his assists, plus his free throws made that represented a team scoring possession. A player's total possessions would be all of his scoring possessions, plus his missed field goals and free throws that weren't rebounded by his team, plus his turnovers.

Scoring possessions= FG - 0.37*FG*Q/R + 0.37*AST + 0.5*FT

Possessions= FGA-(FGA-FG)*OR%+0.37*AST-0.37*FG*Q/R+TO+0.4*FTA

Q= TMAST/TMMIN*5*PLYRMIN - AST

R= TMFG/TMMIN*5*PLYRMIN - AST

OR%= TMOR/(TMFGA-TMFG)

Johnson Effect: A baseball (sabermetric) term that has applications in basketball. It states: "The tendency of teams that exceed their Pythagorean projection for wins in one season to relapse in the following season." (From Bill James' The Baseball Abstract.)

Play Percent: Scoring possessions minus scoring possessions on which no field goal was made (only free throws), divided by possessions minus scoring possessions on which no field goal was made. Approximately the percentage of the time a team will score if not sent to the free throw line.

Play %= FG/(FGA-OR+TO)

Points per Possession: Points divided by possessions. Related terms are Adjusted Points per Game and Overall Rating (or just Rating).

Points per possession= Points scored or allowed/possessions

Adjusted points per game (Adjppg) is just points per possession times the league average of possessions per team per game. The overall rating is points per possession time 100.

Possession: The period of play between when one team gains control of the ball and when the other team gainst control of the ball.

Possessions= FGA-OR+TO+0.4*FTA

The possessions formula is for teams. When applied, a team's offensive and defensive (its opponents' offensive) numbers are both run through the formula, then the average is taken. Almost without exception, the two estimates are within one percent of each other, making the averaging a safe procedure.

Pythagorean 17 Method: A method that gives an expected winning percentage using the fact that the ratio of a team's wins and losses is related to the number of points scored and allowed by the team raised to the seventeenth power.

Expected Winning %=(Pts scored)^17/[Pts scored^17 + Pts allowed^17]

Scoring Possession: Any possession on which at least one point was scored.

Trade Value: (From Bill James) An estimate using a player's age and his approximate value to determine how much value a player has left in his career.

Trade Value= (AV-Y)^2*(Y+1)*AV/190 + AV*Y^2/13

Y= 27- 0.75*Age

A player's Y factor represents an estimate of how many season he has left to play and is always assumed to be at least one and a half years.


Basketball Hoopla, 1988, L. Dean Oliver