Lesson 3: Central Tendency

• Mode - most common value
• Median - value in the middle
• Mean - average
• Uniform distribution
  • Flat line
  • No mode / multiple modes

x-bar = sum(x) / n
mu = sum(x) / N

• Properties of mean
  • All scores in distribution affect mean
  • Mean can be described with a formula
  • Many samples from pop have similar mean
  • Mean of a sample can be used to make inferences about it
  • Extreme values can drastically alter mean
• Properties of median
  • Robust - not affected by outliers
• Normally distributed data generally has a similar mode, median and mean