Mean, Median and Mode¶

Python notebook: https://github.com/daviskregers/data-science-recap/blob/main/01-mean-median-mode.ipynb

Mean¶

• Simply the average value
• Calculated - sum / number of samples
• Example:
  • Number of children in each house on my street
  • 0, 2, 3, 2, 1, 0, 0, 2, 0
  • The MEAN is \(\frac{0+2+3+2+1+0+0+2+0}{9} = 1.11\)

Median¶

• Sort the values and take the value at the midpoint

• Example:

  • 0, 2, 3, 2, 1, 0, 0, 2, 0
  • Sort it:
  • 0, 0, 0, 0, 1, 2, 2, 2, 3
  • ^ - 1

• If you have an even number of samples, take the average of the two in the middle.

• Median is less susceptible to outliers than the mean.
  • Example: mean household income in the US is $72,641, but the median is only $51,939 because the mean is skewed by a handful of billionaires.
  • Median better represents the "typical" american in this example.

Mode¶

• The most common value in a data set
  • Not relevant to continuous numerical data
• Back to our number of kids in each house example
  • 0, 2, 3, 2, 1, 0, 0, 2, 0
  • 0: 4, 1: 1, 2: 3, 3: 1
  • The mode is 0