Information Display

You should use category graphs to show and compare simple positive or negative quantities that are associated with one or more categorical or aggregate data dimensions. If you are considering using multiple graphs, see the Guidelines to Using Multiple Graphs.

Pattern Set Decision Table

	Single-Quantity Graphs	Multi-Quantity Graphs	Category Graphs	Percentage Graphs	Total Graphs
Task: What data do you want to show or compare?	Single quantities with optional thresholds	Relationships between quantitative dimensions	Categories associated with simple quantities	Categories associated with percentages	Categories associated with totals

Pattern Samples

	Bar Graph	Horizontal Bar	Clustered Bar	Horizontal Clustered Bar
User Type	Casual	Casual	Experienced	Experienced
Show quantities associated with one categorical or aggregate data dimension	Yes	Yes	No	No
Show quantities associated with one categorical or aggregate data dimension when categories have long labels or the display area is short and wide	No	Yes	No	No
Show quantities associated with two or more categorical or aggregate data dimensions	No	No	Yes	Yes
Show quantities associated with two or more categorical or aggregate data dimensions when categories have long labels or the display area is short and wide	No	No	No	Yes

Note that key concepts such as categorical data dimension and aggregate data dimension are defined on the main Charts and Graphs Pattern Set page.

Bar Graphs

Bar graphs represent two data dimensions. Each bar usually represents a different category. The bar heights represent an associated quantity. Bars may also represent aggregate data, such as quarterly or yearly sales.

Because bar height represents a quantity, the vertical scale of a bar graph should always include zero. For this reason, variations of bar graphs are most effective for showing values that vary widely or that are close to zero. When showing similar values that are far from zero, the bar heights will tend to look the same. In this case, a category line graph may be appropriate.

Bar Graph

Image 1: Bar Graph

Horizontal Bar Graphs

Use a horizontal bar graph for very long bar labels or for fitting the graph into a rectangular region that is short and wide.

Horizontal Bar Graph

Image 2: Horizontal Bar Graph

Required Screen Elements
Component Type	Required Components	Customizable/Extendable Components
Graph	the graph type for this pattern is Bar and the sub-type is Horizontal Bar	Not applicable

Clustered Bar Graphs

Clustered bar graphs represent three data dimensions. Like a regular bar graph, the bars represent one dimension, with each bar usually representing a different category. The bar heights represent an associated quantity. In addition, each cluster of bars represents a third data dimension, which is typically a hierarchical grouping of the bar categories.

Clustered Bar Graph

Image 3: Clustered Bar Graph

Required Screen Elements
Component Type	Required Components	Customizable/Extendable Components
Graph	The graph type for this pattern is Bar and the sub-type is Vertical Clustered Bar	Not applicable

Horizontal Clustered Bar Graphs

Horizontal clustered bar graphs represent three data dimensions, just like a regular clustered bar graph turned on its side. Use a horizontal clustered bar graph for very long bar labels or for fitting the graph into a rectangular region that is short and wide.

Clustered Bar Graph

Image 4: Horizontal Clustered Bar Graph

Required Screen Elements
Component Type	Required Components	Customizable/Extendable Components
Graph	The graph type for this pattern is Bar and the sub-type is Horizontal Clustered Bar	Not applicable