#ML-Stats  #Stats  #Maths 

Percentiles and Quartiles

A percentile is a value below which a certain percentage of observation or data points lies.

Percentiles show how a given value compares to others. The general rule is that if a value is in the kth percentile, it is greater than K per cent of the total values.

Find percentile of n

P = (n/N) * 100

n = Ordinal rank of values
  = No of values below n
N = Total values in the dataset

P% of the entire distribution falls below the value n

What value exists at percentile x

Value = (x(n+1))100

Quartiles

Q1 - 25 percentile Q2 - 50 percentile - median Q3 - 75 percentile

5 Number Summary & Box plots

  • Minimum
  • 1st Quartile(Q1)
  • 2nd Quartile(Q2)
  • 3rd Quartile(Q3)
  • Maximum