Percentile 75 / 3rd quartile (percentile75)

[ 1 Description ] [ 2 How does it work in the search window? ] [ 3 How does it work in LINQ? ]

Description

This operation returns the highest value below the 75th percentile of a specified field for each grouping occurrence using linear interpolation.

How does it work in the search window?

Before being able to perform this operation, you have to group your data. Be aware that the fields used as arguments for the grouping operation will not be available to select as arguments for the aggregation operation.

After grouping the data, select Aggregation in the search window toolbar, then select the Percentile 75 / 3rd quartile operation. You need to specify one argument:

Argument	Data type

Argument	Data type
Source ^mandatory	integer

The data type of the aggregated values is integer.

Example

In the siem.logtrust.web.activity table, we want to get the highest value below the 75th percentile of the contentLength field in each 5-minute period. Before aggregating the data, the table must be grouped in 5-minute intervals. Then we will perform the aggregation using the Percentile 75 operation.

The arguments needed for the Percentile 75 operation are:

Source → contentLength field

Click Aggregate function and you will see the following result:

How does it work in LINQ?

Group your data using the following structure:

group every server period by field1, field2...
every client period

Then, use select... as... to add the new field that will show the aggregated values. This is the syntax for the Percentile 75 / 3rd quartile operation:

percentile75(integer_field)

See Build a query using LINQ to learn more about grouping and aggregating your data using the LINQ language.

Example

You can copy the following LINQ script and try the example above on the siem.logtrust.web.activity table:

from siem.logtrust.web.activity
  group every 5m
  every 5m
  select percentile75(contentLength) as percentile75_contentLength