A bullet graph (sometimes also called a bullet chart) is a great way to visually compare a measure with a goal, target, or threshold. The bar indicates the measure value, while the line indicates the target. Tableau also defaults to shading to indicate 60% and 80% of the distance to the goal or threshold. The line and the shading are reference lines that can be adjusted (we'll explore how in detail in future chapters):

Let's say that hospital administration has set some goals regarding the time to service, that is, the number of minutes between the time a patient arrives at the hospital and the time they start receiving care. Administration knows that each department has unique capabilities and requirements, so they have defined different goals for each department, as follows:

You maintain these goals in a spreadsheet (here, this is Hospital Goals.xlsx in the Chapter 03 folder). Your goal is to create a visualization that shows the actual averages per department in comparison to the goals that have been set by administration.

We'll build a bullet graph using the Chapter 3 workbook, which contains the Hospital Visits and the Hospital Goals spreadsheet data sources. We'll use these two data sources to visualize the relationship between actual and target minutes to service as you follow these steps:

1. Navigate to the Average Minutes to Service (Bullet Chart) sheet.
2. Using the Hospital Visits data source, create a basic bar chart of the average Minutes to Service per Department. (hint: use the drop-down arrow on the Minutes to Service field on Rows to select Measure | Average. This will set the appropriate aggregation).

3. Sort Department from highest to lowest. At this point, your view should look like this:

4. In the left-hand data pane, select the Hospital Goals data source and then click to select the Minutes to Service Goal field in the data pane under Measures.

5. Open Show Me and select the bullet graph. At this point, Tableau will have created a bullet graph using the fields in the view and the Minutes to Service Goal field you selected. You'll observe that the Department field has been used in the data blend to link the two data sources and that it is already enabled because the Department field was used in the view:

With bullet charts, it can be helpful to visually call out the bars that exceed the threshold. We'll look at creating calculations in depth in the next chapter, but for now, you can complete this example with the following steps:

1. Click the Hospital Visits data source to select it.
2. Right-click an empty spot in the data pane under Dimensions or Measures and select Create Calculated Field.
3. Name the calculated field Over Service Time Goal? with the following code:

AVG([Minutes to Service]) > SUM([Hospital Goals].[Minutes to Service Goal]) 

4. Click OK and drag the new Over Service Time Goal? field from the data pane and drop it on Color.

The calculation returns true when the Average Minutes to Service values is greater than the goal value, and false otherwise. With the calculated field on Color, it becomes very easy to see which departments are over the threshold. The bullet chart makes it easy to see which departments have gone over the threshold that's been set by administration: