Categorical Variables
Tabular Frequency Tables - for distribution of one variable Contingency Tables - for showing the joint distribution
Graphical (Plot) Bar Plots - to display single categorical variable Stacked (Segmented) Bar Plot - to display several
Factors
- A categorical explanatory variable in an experiment is a factor
- The values of a factor are its levels
- A particular combination of values for the factors is called a treatment
Example:
- factor 1: $A$, $B$
- factor 2: $X$, $Y$
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4 treatments: $A X$, $A Y$, $B X$, $X Y$
- Experimental unit - the smallest using to which a treatment is applied,
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and a block - is a group of similar experimental units
- OpenIntro Statistics (book)