Key performance indicators, also known as KPIs, are measurements used to judge how well your business is doing. They lend themselves well to use in visual displays, such as graphs, thermometers, charts, and gauges used in dashboards. A visual of a KPI in a dashboard should not be complicated, should not require elaborate explanation, nor should it be redundant to the actual numeric information.

Dashboards should display key information in a quick-to-digest format. Often, gauges, dials, and thermometers are used incorrectly, causing confusion rather than clarification. If you want to know more than the recommendations in the dashboard analyses in this book, suggested reading about good dashboard design is Stephen Few's Information Dashboard Design.

If we display the current sales in the current month, we hope that it will show a rising number daily. But just a number by itself might be meaningless to most of us. Are sales going up at a faster rate than average sales, sales during the same period last year, or expected or forecasted sales? A dashboard visual conveys that information without the need for elaborate text explanations. A dashboard visual of a specific KPI should allow the user to follow through to investigate more detailed information.