Quartile

As explained in Cyber Threat Hunting

A quartile is a value that divides an ordered dataset into four ranges containing approximately equal numbers of observations.

A quartile is a value that divides an ordered dataset into four ranges containing approximately 25% of the observations each. The lower quartile marks the point below which 25% of values fall, the median divides the data in half, and the upper quartile marks the point below which 75% fall. section 7.1.2

Quartiles support interquartile-range filtering when data is skewed or contains outliers. Keeping values between the lower and upper quartiles reduces noise before calculating variance and standard deviation. section 7.1.2

Filtering connection timing data

For grouped network events, calculate lower and upper quartiles for time_diff_sec, drop rows outside those bounds, and then compute grouped standard deviation, variance, and connection counts. section 7.1.2

Figure 7.4 Quartiles for a nonnormal distribution

Use the quartile box plot to inspect quartile positions in a nonnormal distribution. section 7.1.2

How Cyber Threat Hunting covers it

How deep it goes

Defines three quartiles and applies their bounds to filtering, but defers detailed calculation mechanics.

Examples

Uses time_diff_sec distributions, nonnormal and left-skewed box plots, and grouped network-event filtering listings.

What it assumes

Assumes ordered numerical data and teaches the median and quartile positions directly.

What you can do after

Apply it via pandas to remove timing values outside interquartile bounds before calculating grouped variability.

How it connects

Connects quartiles with interquartile range, median, outliers, skewed data, variance, standard deviation, and box plots.

liveBookmanning.com

Read Cyber Threat Hunting on liveBook Get the book at manning.com

Also explained in

• 

  liveBookmanning.com
  The Well-Grounded Data AnalystA quartile is one of the values dividing an ordered dataset into four equal parts.
• 

  liveBookmanning.com
  Statistics Slam DunkA quartile is a positional statistic that divides an ordered distribution into four equal-probability sections.
• 

  liveBookmanning.com
  Statistics Every Programmer NeedsA quartile is a quantile that divides ordered observations into four equal parts.

Compare how 4 books explain quartile →

Related concepts

• percentileincludes · A percentile is a value in an ordered distribution at or below which a specified proportion of observations falls.
• upper quartileincludes · The upper quartile, or third quartile, is the value marking approximately the 75th percentile of an ordered dataset.
• quantileskind of · A quantile is a value that divides an ordered dataset or probability distribution so that a specified proportion of observations lies at or below it.
• thresholdconfigures · A threshold is a boundary value against which a quantity is compared to determine whether a condition is met or an action or decision is triggered.
• interquartile rangemeasured by · The interquartile range is the difference between the third and first quartiles of a distribution, measuring the spread of its middle half.

This explainer was generated by Manning's knowledge graph from the text of Cyber Threat Hunting. The section links point to the parts of the book it draws on.