NCAA Basketball Ratings Methodology



The Ratings

Predictive Rating - The number of points better the team is than an average team. This rating is the best predictor of future results. Subtracting two teams' predictive rating gives the expected scoring margin on a neutral floor.

Expected Predictive Rating - The quality of the outcome (win or loss) of games each team has played. It's determined by calculating the predictive rating each team would need in order to expect to win the number of games that the team won against its schedule. Since only wins and losses matter, margin of victory does not play a factor in this rating.

Offensive Rating - The offensive component of the Predictive Rating, based on points per play adjusted for level of competition. How many points better the team is on offense compared to an average offense.

Defensive Rating - The defensive component of the Predictive Rating, based on points per play given up, adjusted for level of competition. How many points better the team is on defense compared to an average defense.

Pace - Possessions per game that the team wants to play. Calculated based on possessions per game, adjusted for pace opponents play at.

Improvement - An estimate of the number of points the team improved from beginning to end of season, relative to all other teams. This is calculated based on how the team trended throughout the season.


The Grades

Grades are assigned based on number of standard deviations above or below the average team's season average. An A is greater than 2 standard deviations above average. F is less than 2 standard deviations below average.


Offense/Defense

Throughout this site, offense/defense are broken down into different components:

• First field goal attempt of each possession - Makes up about 45% of variation in offense/defense
  • Shot Categories
  • Close Shots - Two point non-jumpers. Mostly dunks, layups, tip-ins, alley-oops. These are the most efficient field goals as they often have close to 1.2 points per shot (60% shooting percentage). There's also a greater chance of getting fouled on this type of shot, which could lead to freethrows, which are the most efficient way to score.
  • 2 Pt. Jumpers - Two point non-jumpers. Jumpers from all two point distance. Even short two point jumpers generally have a low points per shot (averages below 0.8 or 40% shooting percentage), so are all included in this category, instead of separating by distance.
  • Three Pointers - Any shot behind the three point line. Averages around 1.0 points per shot.
  • Shot Accuracy - Effect on points per shot of making field goals in each shot category (close shots, two point jumpers, three pointers) more or less than average. Regression analysis shows this component accounts for about 80% of the variation in points per shot (or effective field goal percentage).
  • Shot Selection - Effect of the mix of field goal attempts by shot category (close shots, two point jumpers, three pointers) on points per shot. Generally, close shots have highest points per shot, followed by three points, then two point jumpers. Generally a poor shot selection rating is due to more two point jumpers than average or fewer close shots than average. Regression analysis shows this component accounts for about 20% of the variation in points per shot (or effective field goal percentage).
• Second Chance - Makes up about 25% of variation in offense/defense
  • Offensive Rebound Percentage - Percentage of offensive rebound opportunities that a team gets an offensive rebound.
  • 2nd Chance Points Per Possession - Points scored per second (or third, etc) chance opportunity.
  • Points Per Offensive Rebound Opportunity - This takes into account both offensive rebound % and points scored in those extra scoring opportunities. Regression analysis shows variation of this statistic is made up of about 60% by offensive rebound percentage and 40% by second chance points per possession
• Turnovers Per Possession - Makes up about 20% of variation in offense/defense
• Freethrows - Makes up about 10% of variation in offense/defense
  • Freethrow attempts per non-turnover possession
  • Freethrow shooting percentage
  • Freethrow points per non-turnover possession. This is the combined effect of the freethrow attempts per possesion and freethrow shooting percentage. Variation in this statistic is made up of about 70% freethrow attempts and 30% by freethrow shooting percentage.

Offense/Defense Breakdowns

Attempts - Effect of quantity of number of scoring opportunities.

• Close Shots, 2 Pt. Jumpers, Three Pointers - Percentage of the first field goal attempt of each possession that fall into each shot category, adjusted for competition. First field goal attempts of each possession are separated from second (and third..) chances, because for most teams they have a different mix of type of shots and conversion rate.
• Freethrows - Average number of free throw attempts per game expected to attempt against an average opponent, based on NCAA average number of non-turnover possessions
• Second Chance - Offensive rebound percentage against an average opponent.

Conversion Rate - The rate at which the opportunities are converted to points

• Close Shots, 2 Pt. Jumpers, Three Pointers - Points per shot expected against an average defense.
• 1st FG Attempt - Points per shot expected against an average defense for the first field goal attempt of each possession.
• Freethrows - Free throw percentage against an average opponent. Opponent has little effect on free throw conversion rate, but they do have some control over which opponent's players go to the free throw line, which does affect the team's free throw percentage
• Second Chance - Second chance points expected to score per offensive rebound against an average opponent.

Total Effect - The total effect for each category that takes into account attempts and conversion rate.

• Close Shots, 2 Pt. Jumpers, Three Pointers - Number of points expected to be scored per game from each category above or below an average team, based on the NCAA average number of field goal attempts in a game.
• Freethrows - Number of points expected to be scored per game from each category above or below an average team, based on the NCAA average number of field goal attempts in a game. This is essentially ranking of points per shot or effective field goal percentage for the first shot of each possession, adjusted for opponent.
• Freethrows - Average number of free throws expected to be made per game against an average opponent based on NCAA average number of non-turnover possessions.
• Second Chance - Second chance points per offensive rebound opportunity expected against an average opponent. This takes into account both offensive rebound percentage and how many points are converted from the additional opportunity.
• Turnovers - Percentage of possessions turn the ball over against an average opponent
• Total Offense - Number of points expected to be scored per game against an average opponent more or less than an average team based on NCAA average number of possessions.

Game Detail

The game grades are assigned based on performance in each category adjusted for strength of competition. So a 1.00 points per shot game could be an A against a very good defensive team, but an D against a poor defensive team, for example.

The stats in the game detail table are raw, unadjusted for opponent strength.

Abbreviations:
2 C - Close two pointers
2 L - Long two pointers
3 - Three pointers
Off Reb - Offensive rebounding percentage
PPP - Points per possession. Points scored per second chance opportunity (after offensive rebound). This takes into account opportunities where there are turnovers or freethrows, so is not comparable to points per shot in first field goal attempt section.
Att - Attempts
Perc - Shooting Percentage

Total offense and defense stats are points per possession.
Shot Accuracy section shows shooting percentage of the first shot of the possession of each type of shot.
Shot Selection section shows the percentage of all first shots of the possession that are each type of shot.
The total statistic in the shot accuracy and shot selection sections is the effect that the shot accuracy and selection would have on a game with the national average number of possessions.



All-Time Rankings

All-Time Rankings are constructed by merging the ratings of all individual years. Since all ratings are points above or below the average team that year, the all-time ratings should be seen as quality of the team in the context of the era in which they played, and not necessarily a measure of who would win if matched up. The absolute level of play in college basketball likely changes over time due to resources available to athletes, the number of early exits to NBA, rule changes, and many other factors.

Offensive and defensive ratings require an estimate of number of possessions to be known in order to calculate the efficiency of the offense and defense. For recent years, the estimated number of possessions is calculated using field goal attempts, free throw attempts, turnovers, and offensive rebounds. When complete statistics aren't available for some teams/years in the past, the required stats are estimated using regression analysis on the statistics that are available. Analysis shows that in most cases, estimating these statistics does not have a significant effect on the offensive/defensive split. As the Predictive Ratings and Expected Predictive Ratings do not require number of possessions, they are calculated the same way for older seasons as they are for more recent seasons.


Season Simulation

A simulation of the remainder of the current season is performed to determine the chance of various outcomes occurring. It simulates every aspect of the season including each regular season game, conference tournament games, ncaa tournament selection, and lastly the ncaa tournament. This produces every team's chances of many different outcomes including outcome of each game, selection into NCAA tournament, tournament seeding, conference championship, national championship, and many more that can be found on the team pages.

Also recorded is the projected chance of each outcome if the team wins or loses the next game, which can also be found on the team pages. Actual chances shown after the next update might differ slightly (or in some cases greatly) depending on how the team played against their next opponent and the outcome of other teams' games that might affect their chances.



Any other questions, please contact me at inccstats.bball@gmail.com