A unit chart can be used to show individual items, often using shapes or symbols to represent each individual. These charts can elicit a powerful emotional response, because the representations of the data are less abstract and more easily identified as something real. For example, here is a chart showing how many customers had late shipments for each Region:
The view was created with the following techniques:
- The view is filtered where Late Shipping is True. Late Shipping is a calculated field that determines if it took more than 14 days to ship and order. The code is as follows:
DATEDIFF('day', [Order Date], [Ship Date]) > 14
- Region has been sorted descending by the distinct count of Customer ID.
- Customer ID has been placed on Detail so that there is a mark for each distinct customer.
- The mark type has been changed to Shape and the shape has been changed to the included person shape in the Gender shape palette. To change shapes, click the Shape shelf and select the desired shape(s), as shown in the following screenshot:
The preceding unit chart might elicit more of a response from regional managers than a standard bar chart when they are gently reminded that poor customer service impacts real people. Granted, the shapes are still abstract, but more closely represent an actual person. You could also consider labeling the mark with the customer name or using other techniques to further engage your audience.
Concrete shapes, in any type of visualization, can also dramatically reduce the amount of time it takes to comprehend the data. Contrast the amount of effort required to identify the departments in these two scatterplots:
Once you know the meaning of a shape, you no longer have to reference a legend.
Placing a discrete field on the Shape shelf allows you to assign shapes to individual values of the field.