Calcolatore Rilevamento Valori Anomali — Formula

How to Detect Outliers Using the IQR Method

Formula

IQR = Q3 - Q1

Lower Fence = Q1 - 1.5 * IQR

Upper Fence = Q3 + 1.5 * IQR

Values below the lower fence or above the upper fence are flagged as potential outliers. The 1.5 multiplier is Tukey's convention. Using 3.0 instead identifies extreme outliers.

Esempio Risolto

Q1 = 30, Q3 = 70. Is 95 an outlier?

  1. IQR = 70 - 30 = 40
  2. Lower fence = 30 - 1.5*40 = 30 - 60 = -30
  3. Upper fence = 70 + 1.5*40 = 70 + 60 = 130
  4. 95 is between -30 and 130, so it is NOT an outlier
  5. It would need to exceed 130 to be flagged