NCAA POWER INDEX CALCULATION METHOD
Step 3 - Determining The Team's Initial Ratings
A team's rating depends on part on the ratings of its opponents. The problem is, each opponent's rating depends on this team's NPI.
How are we supposed to calculate them?
The method used is "recursion" - use the current values to calculate the next values, then use those values to create another set of values, and so on.
Continue until each value changes by a small enough amount that, for all intents and purposes, the ratings are not going to change.
I use 10-10 (i.e. 0.0000000001).
"Yes, but what do we use for the initial values?"
For all intents and purposes, zero. However, the initial rating calculation is slightly different than just "start with zero and go through the normal process."
Each team's initial NPI rating is calcualted as follows:
- For each opponent, multiply its Adjusted Win Percentage by the game's Game Value;
- Add up these values;
- Divide by the sum of the games' Game Values;
- Multiply this number by the SOS Dial value, then divide by 100.
Example
Here is William Paterson's 2025 football initial rating calculation:
| Opponent | Adj
Wins | Adj
Losses | Adj
Win % | Game
Value | Adj % x
Game Value |
|---|
| Western Connecticut | 4.9 | 4 | 55.056180 | 0.9 | 49.550562 |
| Salve Regina | 6 | 4 | 60 | 1.1 | 66 |
| Moravian | 2 | 8 | 20 | 1.1 | 22 |
| Castleton | 2 | 8 | 20 | 0.9 | 18 |
| College of New Jersey | 6 | 4 | 60 | 0.9 | 54 |
| Rowan | 7.55 | 2.75 | 73.300971 | 0.9 | 65.970874 |
| Christopher Newport | 10 | 0 | 100 | 1.1 | 110 |
| Salisbury | 9.1 | 0.9 | 91 | 0.9 | 81.9 |
| Kean | 2.9 | 7.1 | 29 | 1.1 | 31.9 |
| Montclair State | 5.1 | 5.1 | 50 | 1.1 | 55 |
The sum of the (Adjusted Win Percentage x Game Value) values is 554.321436, and the sum of the Game Values is 10, so the initial NPI = 554.321436 / 10 = 55.432144.
"Why is Rowan's adjusted wins different than the others?" Its game against Case Western Reserve was declared a 17-17 tie after it was stopped multiple times for weather.
Previous - Step 2 - Determine Adjusted Win Percentages
Next - Step 4 - Determine Game Ratings