Stats

Chapter 1: Analyzing Categorical Data  

  • Categorical Variables: Place individuals into one of several groups or categories  

  • Analyze a distribution by displaying it with a bar graph or pie chart  

  • Bar: “count of” 

  • Pie: “Percent of” 

Bar Graphs compare several quantities by comparing the heights of bars that represent those quantities  

🔅Make bars equally wide 🔅 

 

Two-Way Tables and Marginal Distributions  

 

Two way-table: Describes two categorical variables, organizing counts according to a row variable and a column variable  

Marginal distribution: Distribution of values of that variable among all individuals described by the table. 

How to examine a marginal distribution:  

  1. Use the data to calculate the marginal distribution (%) of the row or column totals  

  1. Make a graph to display the marginal distribution  

 

Relationships Between categorical variables  

A conditional distribution of variable describes the values of that variable among individuals who have a specific value of another variable  

How to examine or compare conditional distributions:  

  1. Select the row(s) or column(s) of interest  

  1. Use the data in the table to calculate the conditional distribution (%) of the row(s) or column(s)  

  1. Make a graph to display the conditional distribution. 

  • Use side by side bar graph or segment bar graph to compare distributions