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Statistics for Data Science · Module 2 of 10

Measures of central tendency and spread

Describe data with averages and variability.

📖 Key ideas

  1. Mean is the average; median is the middle; mode is the most frequent.
  2. Median resists outliers better than mean.
  3. Range = max − min.
  4. Variance and standard deviation measure spread around the mean.
  5. IQR (Q3 − Q1) measures spread of the middle 50%.
💡 Real-life example: Mean salary of a room changes a lot if a billionaire walks in; median hardly moves.
MeanAverage value
MedianMiddle value
Standard deviationTypical distance from the mean
IQRInterquartile range