| Word | Definition |
| Frequency Table | Record totals and category names.
Distribution of categorical variables. |
| Pile | Count number of data values in each category of interest. |
| Relative Frequency Table | Counts are expressed as percentages.
Distribution of categorical variables. |
| Area Principle | Each data value should be represented by the same amount of area.
Equal width and equal spacing. |
| Bar Chart | Show counts for each category.
Distribution of categorical variables.
Bars don't touch (Area Principle). |
| Vertical (Y) Axis of Bar Chart | Frequency or relative frequency (100%). |
| Horizontal (X) Axis of Bar Chart | Categories. |
| Relative Frequency Bar Chart | Show percent for each category. |
| Pie Chart | Slice into pieces proportional to the fraction of the whole.
In percents, whole circle adds up to 100%. |
| Contingency (Two-Way) Table | Two categorical variables shown individually distributed along each variable.
Contingent on the value of the variable.
Cells give counts NOT totals. |
| Marginal Distribution | Distribution of one variable.
From totals on margins of contingency tables.
Total per category / The whole. |
| Conditional Distribution | Distributions of one variable for just the individuals who satisfy some condition on another variable (restricts).
Value of cell / Row or Column total. |
| Independent Variable | Segmented bar chart shows IDENTICAL values.
Means two variables have NO ASSOCIATION. |
| Dependent Variable | Segmented bar chart shows DIFFERENT values.
Means two variables ARE ASSOCIATED. |
| Segmented Bar Chart | Conditional distribution of categorical variable within each category of another variable.
By percents.
Each bar treated as a whole (like a pie chart). |
| Simpson's Paradox | When averages are taken across different groups, they can appear to contradict the overall averages. |
