Adjusted Efficiency Differential (AED) adjusts basic efficiency differential (offensive efficiency minus defensive efficiency) to account for opponent strength and game location (road/home). It aims to single out the rest days impact more precisely.
Adjusted Efficiency Differential (AED) Formula = (Expected Efficiency Differential) – (Actual Efficiency Differential)
Because AED measures expected efficiency “relative” to the actual efficiency, a negative AED might be just fine. Here are samples of what negative AED cases mean:
- If “Expected ED” is a negative value, while the “Actual ED” is positive, then the AED becomes negative. (ie UNDERDOG team WINS the game.)
- If “Expected ED” is a negative value, while the “Actual ED” is negative and greater than expected, then the AED might be negative. (ie UNDERDOG team LOSES by a SMALLER MARGIN than expected.)
- If “Expected ED” is a positive value, while the “Actual ED” is positive and greater than expected, then the AED might be negative. (ie FAVORITE team WINS by a LARGER MARGIN than expected.)
If you still need further explanation, we recommend getting a spreadsheet which has game-by-game Vegas lines and OEFF and DEFF values. By looking at VEGAS spreads, you can identify favorites and underdogs. By subtracting OEFF from DEFF, you can calculate “Actual ED” for each team in a game.