Introduction

Descriptive Statistics (Exploratory Data Analysis) #

• Summary Statistics
• Used to understand and define the sample data
• Measures of Central Tendency
  • Mean - average, sensitive to outliers
  • Median - middle point of the data, robust to outliers
  • Mode - most frequent value
• Measures of Dispersion
  • Variance - average of the squared distance of each point to the mean
  • Standard Deviation - how much our data is spread out around the mean, most commonly used
  • Range - difference between largest and smallest observation in the data, sensitive to outliers
  • Interquartile Range - difference between the 25th and 75th percentile of the data
• Don’t allow us to make conclusions beyond the data we’ve analyzed or reach conclusions regarding any hypothesis we might have made

Inferential Statistics #

• Used to make generalizations about a population
• Key
  • Make sure samples are representative
  • Selecting a good sample is critical for making inferences about the population
• Sampling error