95th Percentile Calculation

The 95th percentile is a number that is greater than 95% of the numbers in a given set. The reason this statistic is so useful in measuring data throughput is that it gives a very accurate picture of the maximum traffic generated on an interface. This is a standard measure used in interpreting performance data. This 95th percentile is the highest value left when the top 5% of a numerically sorted set of collected data is discarded. It is used as a measure of the peak value used when one discounts a fair amount for transitory spikes. This makes it markedly different from the average.

The following example would help you understand it better. 

  • Consider if the data collected for CPU Utilization are 19, 15, 9, 6, 3, 27, 17, 29, 8, 10, 7, 13, 12, 24, 23, 20, 4, 25, 14, 2, 26, 16, 1, 5, 22, 30, 28, 11, 18, 21.
  • The total number of entries K = 30.
  • Since we are calculating the 95th percentile, multiply the number of entries (K) with 0.95.
  • Then, 0.95 x 30 = 28.5 (Let's take this as N).
  • Arrange the values in ascending order.
  • Then, the values will be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30.
  • The 95th percentile value is 28.
  • Leaving the values greater than 28.5, the list becomes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28.
  • The average of the above numbers will be the 95th percentile average.
  • Here, the 95th percentile average is ((1+2+3+...+27+28)/28) = 14.5

The unit for threshold is based on the unit of the monitor ie., for all utilization monitors like CPU, Memory, Disk, Interface Rx/Tx etc., the threshold will be in percentage. For Rx/Tx Traffic, the threshold will be in bps (bits per second). For any other monitor like Free Disk Space in MB, the threshold unit will be in MB.

 

Video Zone
OpManager Customer Videos
Altaleb Alshenqiti - Ministry of National Guard - Health Affairs
  
  •  IT Admin from "Royal flying doctor service", Australia
     Jonathan ManageEngine Customer
  •  Michael - Network & Tech, ManageEngine Customer
     Altaleb Alshenqiti - Ministry of National Guard - Health Affairs
  •  David Tremont, Associate Directory of Infrastructure,USA
     Todd Haverstock Administrative Director
  •  Donald Stewart, IT Manager from Crest Industries
     John Rosser, MIS Manager - Yale Chase Equipment & Services
 Pricing  Get Quote