Chapter 12: Statistics

Measures of Central Tendency

Mean (Average)

Mean = Sum of observations / Number of observations

For grouped data: Mean = Σfx / Σf

Median (Middle Value)

Arrange in order, find middle value.

  • Odd n: Middle term
  • Even n: Average of two middle terms

Mode (Most Frequent)

Value with highest frequency.

Example

Data: 2, 3, 5, 5, 5, 7, 9

  • Mean = (2+3+5+5+5+7+9)/7 = 36/7 = 5.14
  • Median = 4th value = 5
  • Mode = 5 (occurs 3 times)

When to Use

MeasureBest For
MeanData without outliers
MedianData with outliers
ModeCategorical data

🎉 Chapter 12 Complete!