Assist Ratio is the percentage of a team’s possessions that ends in an assist.

Assist Ratio Formula=(Assists)*100)/ [(Field Goal Attempts)+(Free Throw Attempts*0.44)+(Assists)+(Turnovers)]

The Herfindahl Index (HHI) can be used to measure scoring balances for NBA teams.

HHI calculation for each team: (1) divide each player's points scored by the total number of points scored by the team, (2) square that result for each player, (3) sum those squares.

The method that relates winning percentage to points scored, points allowed, the standard deviations of points scored and allowed, and the correlation between points scored and allowed.

Correlated Gaussian Winning Percentage Formula=NORM{(Points Scored-Points Allowed)/[Standart Deviation(Points Scored-Points Allowed)]}
NORM means to take the percentile of a normal distribution.

The number of points a team allows per 100 opposing team possessions.

 Defensive Efficiency Fomula=100*(Points Allowed/Possessions)

The metric of a team's ability to get defensive rebounds.

Defensive Rebounding Percentage Formula=(Team Defensive Rebounds)/[(Team Defensive Rebounds)+Opponent's Offensive Rebounds)]

A metric that indicates the average age of the team, weighted by the playing time of players on the roster.

The metric which combines 2-point shots with 3-point shots.

Effective Field Goal Percentage Formula=[(Field Goals Made) + 0.5*(3P Field Goals Made)]/(Field Goal Attempts) 

The numerical gap between a team's offensive efficiency and defensive efficiency. The differential represents what each team did for the entire season and a team’s efficiency differential is a better predictor of future success.

Efficiency Differential Formula=(Offensive Efficiency)-(Defensive Efficiency)

Four factors are box score derived metrics that correlate most closely with winning basketball games. These factors also identify a team’s strategic strengths and weaknesses. Four factors can be applied to both a team's offense and defense, hence it gives us eight factors.

• Shooting the ball

Effective Field Goal Percentage=(Field Goals Made) + 0.5*3P Field Goals Made))/(Field Goal Attempts)

• Taking care of the ball

Turnover Rate=Turnovers/(Field Goal Attempts + 0.44*Free Throw Attempts + Turnovers)

• Offensive rebounding

Offensive Rebounding Percentage = (Offensive Rebounds)/[(Offensive Rebounds)+(Opponent's Defensive Rebounds)]

• Getting to the foul line

Free Throw Rate=(Free Throws Made)/(Field Goals Attempted) or Free Throws Attempted/Field Goals Attempted

The ability to get to the free throw line, and the ability to make free throws. Two metrics are used the measure free throw conversion.

(Free Throws Attempted)/(Field Goal Attempts) explains how often a team shoots free throws

(Free Throws Made)/(Field Goal Attempts) explains how well a team shoots at the line in addition to how often they get there

When two teams meet we can calculate the expected winning percentages using the Log5 formula.

WINNING PERCENTAGE OF TEAM A against TEAM B = W%(A)*(1 - W%(B))/(W%(A)*(1 - W%(B)) + (1 - W%(A))*W%(B))

Dividing opponent fast break points by opponent steals might give us an idea of how teams execute "transition defense".

Transition Defense Metric=(Opponent Fast Break Points)/(Opponent Steals)

Dividing fast break points by steals might give us an idea of how teams execute "transition offense".

Transition Offense Metric=(Fast Break Points)/(Steals)

The number of points a team scores per 100 possessions.

Offensive Efficiency Formula=100*(Points Scored)/(Possessions)

The metric of a team's ability to get offensive rebounds.

Offensive Rebounding Percentage Formula=(Offensive Rebounds)/[(Offensive Rebounds)+(Opponent's Defensive Rebounds)]

The total number of possessions a team uses in a game.

Pace Formula=[240/(Team Minutes)]*(Possession_team+Possession_opponent)/2

The metric that indicates the percentage of the time a team will score if not sent to the free throw line. 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.

Play Percent Formula= Field Goals Made/(Field Goals Attempted-Offensive Rebounds+Turnovers)

The numerical gap between points scored and points allowed. Wins in close games tend not to reflect a team's true skill. Teams that start the season with a better record than their point differential tend to slow down and vice versa. Point differential is also a better predictor of future performance than win-loss record.

Point Differential Formula=(Points Scored)-(Points Allowed)

When a team commits a turnover, the scoring crew records the turnover. On the following opponent possession, if the opponent scores, the scoring system credits that opponent with a "point off a turnover.

Arguably the most important discovery in statistical analytics in basketball. 

A possession ends

(1) by making a field goal attempt;

(2) by missing a shot and not getting the offensive rebound;

(3) by turning the ball over;

(4) by going to the line for two or three shots and either making the last shot or not getting the rebound of a missed last shot.

Two teams in any given game are essentially limited to the same number of possessions.

Basic Possession Formula=0.96*[(Field Goal Attempts)+(Turnovers)+0.44*(Free Throw Attempts)-(Offensive Rebounds)]

More Specific Possession Formula=0.5 * ((Field Goal Attempts + 0.4 * Free Throw Attempts - 1.07 * (Offensive Rebounds / (Offensive Rebounds + Opponent Defensive Rebounds)) * (Field Goal Attempts - FG) + Turnovers) + (Opponent Field Goal Attempts + 0.4 * Opponent Free Throw Attempts - 1.07 * (Opponent Offensive Rebounds / (Opponent Offensive Rebounds + Defensive Rebounds)) * (Opponent Field Goal Attempts - Opponent FG) + Opponent Turnovers)).
This formula estimates possessions based on both the team's statistics and their opponent's statistics, then averages them to provide a more stable estimate.

A subjective evaluation tool for the NBA teams which rates the entire league from top to bottom. NBA power rankings are based mostly on how good teams really are, with recent performances taken into partial consideration. The NBA.com does the power rankings job by using the offensive and defensive efficiencies.

Find out the NBA Teams' power rankings in graphics form which helps readers get a better understanding about exactly where the teams currently stand at.

A formula that simply uses a team's net overall point differential (PD=points differential) rather than points scored and point allowed.

Each point of differential translates to 2.7 wins over the course of the season.

Projected Win%=[(Points Differential)*2.7)+41]/82

The method that gives an expected winning percentage using the ratio of a team's wins and losses is related to the number of points scored and allowed.

Expected Winning Percentage Formula=(Points Scored)^16.5/[Points Scored)^16.5 + (Points Allowed)^16.5)]

The Relative Percentage Index (RPI) is widely used to produce power ratings. Unlike most power rating systems, the RPI does not consider margin of victory or how well a team has played. It only considers whether a team won or lost. In fact, the RPI is based entirely on winning percentage.

It essentially measures a team’s strength of schedule and how a team does against that schedule. It is based 25% on a team’s winning percentage, 50% on the winning percentage of their opponents, and 25% on the winning percentage of their opponent’s opponents.

Rating Percentage Index (RPI) Formula=.25*(Team's Winning Percentage)+.50*(Opponents'  Average Winning Percentage)+0.25*(Opponents' Opponents'  Average Winning Percentage)

For example if;
Atlanta is 4-1 (W/L Pct= .800)
Atlanta's opponents averaged a 12-8 (W/L Pct.= .600) record
Atlanta's opponents' opponents averaged a 64-16 (W/L Pct = .800) record, then,
RPI for Atlanta is = (0.25 * .800) + (0.5 * .600) + (0.25 * .800)=.700

Simple Rating System (SRS); a team rating that takes into account average point differential and strength of schedule.

The rating is denominated in points above/below average, where zero is average. More information about calcution of SRS.

Strength Of Schedule (SOS) represents a team's average schedule difficulty faced by each team in the games that it's played so far or for all season. The schedule difficulty of a given game takes into account the rating of the opponent and the location of the game.

Strength of schedule in the NBA has not been considered nearly as important as in the NFL or as in the NCAA basketball since the NBA teams play each other at least twice. Much of the schedule differences between teams come down to road trips, back-to-backs, afternoon games for example.

Strength of schedule can be calculated in many ways and all methods asssign a greater SOS number to a more difficult schedule.

Methods for Calculating Strength Of Schedule

SOS can be calculated by the help of Relative Percentage Index which incorporates W/L records of opponents and opponents' opponents. This method is being used by ESPN. John Hollinger explains the calculation of SOS.

Simple Rating System (SRS) also incorporates strength of the schedule by employing margin of victory (MOV) and the results can be found at basketball-reference.com

Another way used by Kenneth Massey is explained here.

Jeff Sagarin is also in charge of SOS ratings.

Turnover Ratio is the percentage of a team’s possessions that end in a turnover.

Turnover Ratio Formula=(Assists)*100)/ [(Field Goal Attempts)+(Free Throw Attempts*0.44)+(Assists)+(Turnovers)]

Value of Ball Possession (VBP) is the league’s average points per possession. If the NBA teams scored an average of 95.0 points per 100 possessions, that makes the VBP .95.