Data Science Classroom Series – 28/Oct/2021


  • Variability describes how far apart data points lie from each other & from center of the distribution
  • Variability is also referred as spread, scatter or dispersion & is most commonly measured with the following
    • Variance: Variance measures the dispersion of set of data points around the mean
    • Standard deviation: average distance from mean
  • We would have different formulas for
    • Population Data
    • Sample Data
  • Variance:
    • Population Variance:
      • Formula: Preview
    • Sample Variance:
      • Formula: Preview
  • Lets calculate variance for a sample data Refer Here Preview Preview
  • Standard Deviation
    • Sample Standard Deviation formula Preview
    • Population Standard Deviation formula Preview Preview
  • You have the annual personal income from 11 people from Hyderabad. Decide whether you need to use sample or population formula for variance.
    • Calculate the variance and standard deviation
    • Refer Here for the excel Preview Preview
  • Coeffecient of variation:
    • This is referred as relative standard deviation
    • Formula: standard deviation/mean
    • Refer Here this excel sheet and calculate standard deviation for new york and hyderabad pizza prices Preview
  • Exercise: Calculate standard deviation and coefficient of variation for the following excel Refer Here

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