March 2, 2014
Although it's a few weeks before too much will be made of these, I have begun calculating various measures of team success in 2014.
This is an introduction to some of the analysis included on this site.
These ratings are published daily along with some meta-rating variations:
The RPI is the "standard" NCAA measure of team results. "Standard" has to be in quotes because the committee responsible for
each sport's tournament is allowed to make whatever changes it wants to the basic formula.
nRPI is the variation adopted by the baseball committee beginning in 2013. It replaced a system of bonuses and penalties
for top-team wins and bottom-team losses or playing too many games vs non-D1 opponents with a definition of
winning percentage1 that gives less value to home wins and road losses and more to road wins and home losses.
The base RPI formula is simpler to state than it is to explain. It is 25% winning percentage plus 50%
oppenents' winning percentage (OWP2) plus 25% Opponents' Opponents winning percentage
I publish the nRPI with a comparison to the base and the SOS components of the formula (which are the same
for both variants) but for any analysis that depends upon opponents' values I only use the base RPI values.
Boyd Nation's ISR as amended for home field advantage (Tweaking the ISR's)
and margin of victory.
I label this ISRm to distinguish it from the ISR without the margin of victory adjustment, to which I may occasionally refer. Unless
explicitly stated otherwise textual references to ISR are based upon the ISRm calculation.
The Iterated Strength of Victory is my modification of the ISR algorithm that uses a variable adjustment for each game based
upon the SOV4 for each game compared to the mean SOV for all games.
The ISOV is to the (original) ISR as Jeff Sagarin's "pure points" is to his "ELO Chess" rating. It is not as good a measure of past
performance as the ISR or RPI but it is useful in that it provides a mechanism for a SOS-adjusted scoring
stats, which in turn can be used to provide a predictive rating.
For each of the ratings these reports are updated daily.
||This is the basic report to analyze game results according to the specific rating.
|(null)||Rank by PA()|
Sum of defeated opponents' aSOS values for each game won ÷ games played
|Team||Team name links to the team's gory details page.
|Rec||The usual W-L-T|
|Conf||Team's conference affiliation|
|Rank||Team's ordinal ranking for the rating|
|rating||Team's rating value|
|SOS||The average of opponents' rating values|
Sum over all wins of opponents' rating divided by games played. This accounts for the inevitable rating inflation
caused by losing to good teams.|
Average of opponents' aSOS values. Possibly more indicative of schedule strength than SOS for rating.
|vs Opp Ranks
||Records vs Opponents' rating Ranks is an index to the "gory details" for each team sorted by a "better wins compared to worse losses"5 algorithm.|
|R′||Team's rank based upon the better-win—worse-loss criterion.|
|Team||Link to the team's gory details page for the rating.|
|Conf||Team's conference affiliation|
|Rnk||Team's rank for this rating|
|vs...||record vs teams ranked 1-25, 26-50,…|
Interconference results weighted by opponents' rating values.
| ||Conference rank|
|CaSOS||Sum of opponents' ranks in wins divided by number of games played|
|Conf||Link to details by opponent conference|
|SOS(W)||Average opponents' rating for wins|
|W||# wins vs teams from other conferences|
|WP||Winning Percentage vs teams from other conferences|
|L||# losses to teams from other conferences|
|SOS(L)||Average opponents' rating for losses|
|SOS||Average opponents' rating for all games vs teams from other conferences|
| ||SOS rank|
The detail section includes a line for each opposing conference that serves as an index to the interconference results in descending WP order.
|Conf||Link to the conference's results against teams from other conferences|
|SOS||Average opponents' rating for teams from the other conference|
|(W)||Average opponents' rating in the conferences teams' wins|
|W||# wins by conference teams against teams from the other conference|
|WP||Winning percentage against teams from the other conference|
|L||# losses by conference teams to teams from the other conference|
|(L)||Average opponents' rating in the conference teams' losses|
|Opp C||Link to the game results for Conf vs Opp C|
|SOS||Average Conf team rating in games vs Opp C (the other conference's SOS)|
These are also published daily, but are not strictly "ratings."
This uses the SOS as defined by opponents' ISOV ratings to adjust runs-scored and -allowed.
| ||The first column is a rank assigned by comparing the teams' adjusted scoring against that of every other team.|
|Team||Link to the ISOV-based gory details page for the team|
|Rec||Team's record vs D1 opponents|
|RS||Average runs scored|
|←||Rank for RS|
|→||Rank for NRS|
|NRS||Average runs scored normalized for SOS|
|NRA||Average runs allowed normalized for SOS|
|←||Rank for NRA|
|→||Rank for RA|
|RA||Average runs allowed|
|MOV||RS − RA|
|←||Rank for MOV|
|→||Rank for NMOV|
|MOV||NRS − NRA|
This report is described in Too early Ratings. The column headings are:
|→||Team rank using WtdWins|
|WtdWins||WW weighted by number and length of path − weighted LL|
|SOWP||(WW + TT÷2) / (WW+LL+TT+UU)|
|Rank||Team rank by SOWP|
|WW||# of teams B for which the shortest A⇒B path is shorter than B⇒A, or
if the path lengths are equal there are more A⇒B than B⇒ paths|
|LL||# of teams B for which the shortest A⇒B path is longer than B⇒A, or
if the path lengths are equal there are more B⇒B than A⇒ paths|
|TT||# of teams B for which the shortest A⇒B path is the same length as B⇒A and
there are equal numbers of such paths in each direction|
|UU||# of teams B for which there are no A⇒B or B⇒A paths|
|Team||Link to team page listing the shortest paths to each other team for which there are paths in either direction|
|D1W||# of series wins (or ties)|
|D1L||# of series losses|
|NT1||# of teams B such that length A⇒B is 1|
|NTn||# of teams B such that length A⇒B is n|
| 1||RPIwins = 0.7×HomeWins+1.3×RoadWins+NeutralWins|
RPITies = 0.7×HomeTies+1.3×RoadTies+NeutralTies
RPILosses = 0.7×RoadLosses+1.3×HomeLosses+NeutralLosses
|RPIWP = ||RPIwins+(RPIties÷2)|
| 2||OWP is the average of opponents' winning percentage not including games against
the team for which OWP is calculated.|
| 3||OOWP is the average of opponnets' OWP values. Note that this does
include results of games involving the team for which OOWP is calculated.|
|SOV = ||Winning Score − Losing Score|
|Winning Score + Losing Score|
| 5||The "better wins compared to worse losses" algorithm
uses the opponent rank to assign a value to the win (or loss).|
sort value = (#teans+1 - opponent rank) for wins minus opponent rank for losses over all games played.
Higher values are better.
In memory of