Most people who see healthcare maps every day don’t give much thought to their content and cartographic execution. Titles display the purpose of a healthcare map, scale bars display distance, sources explain where the data originated, and legends identify the attributes on a map. All of these cartographic elements combined embody the important final touches that make healthcare maps readable and useful. Cartographic elements help those looking at the map understand the various layers and data without having to concentrate, ask questions, or decipher. This is why the choices made on the final touches of healthcare maps are the most essential part of the map-making process.
The title of a healthcare map shows its purpose. It tells the map reader what they are looking at and why. Titles should give the viewer general high-level information such as the location or the type of geography used in the analysis. A good example would be “Memorial Medical Center: Inpatient Discharges by ZIP Code.” At Stratasan, we center our titles and have them take up no more than two lines of text. We like using a thicker, yet easily readable font that does not appear too bulky or distract from the rest of the map.
Scale bars help viewers visually understand the distances on a healthcare map. There are multiple ways to display scale on a map: a representative fraction (e.g. 1:32,000), a verbal scale (e.g. one inch to 10 miles), or a bar scale (which is like a distance ruler on the map). At Stratasan, we use a bar scale. This is because it is an easy and effective way for map readers to perceive distance visually and does not require a strong knowledge of map scaling mechanics or math. Our standard is to place our scale bars at the bottom left of the map where they are easy to find and use without being in the way.
The data sources used in creating the map should always be displayed on the final product. We use a small (10-12 point) font that shows the data’s source and what year the data was published. We place the source information at the bottom right of our maps.
Legends display the translation of the most important attributes on a map. The main idea is that a legend only includes the information on a map that is not inherently understood by the map reader. Layers like roads, counties, or labeled icons are usually omitted from the legend. This is because their meaning is evident and requires no explanation or translation. Including map layers like those take up room in the legend box and distract from the map. In Stratasan maps, we put the representative symbols of each attribute on the left side of the legend box and their definitions to their right. Ordering of attributes in the legend is of critical importance. Items should be ordered by their placement on the map and by their importance. They should also be organized to keep the profile of the legend box as small, and out of the way, as possible. Normally, Stratasan places their legend box in the bottom left corner of the map or in a margin area off to the bottom right side of the map’s boundary box.
It should be noted that we DO NOT use a north arrow (compass rose) on our maps. Almost all maps that are used are aligned north to south; we believe that a compass rose should be placed on maps only if north is not at the top of the map. The addition of a compass rose is almost always a distraction that takes away from the real purpose of the map.
Below are a few examples of legends we use at Stratasan:
This map of graduated symbols representing patient charges and reimbursements by payor also displays roads and the location of Winter Haven Hospital. These two features don’t need to be explained. However, the patient charges, reimbursements, and payor symbols do and are included in the legend.
When large amounts of information need to be displayed in a legend, multiple columns of information within the legend box are usually needed. In this case, it is for a variable type and value column for the data in each map frame. Payor is simple and is displayed by color. Charges and reimbursements are aligned top to bottom from lowest to largest values. Since the values given do not explain the data’s meaning, “Payor”, “Charges”, and “Reimbursements” headers were included. This way the map reader can understand the meaning of the symbols inherently.
Sometimes legends need to cover both values and categories (like the one above). Specifically, this map displays Winter Haven’s primary competitor’s inpatient discharges by ZIP code (Lakeland Regional Health). The values for the shaded ZIPs as well as the outlines signify where Winter Haven’s service area is, showing the map reader all of the information they need to interpret the insights the healthcare map provides quickly and easily.
Dominant Tapestry Segmentation by block group is a cornerstone of Stratasan’s psychographic market intelligence analysis. Like the previous map, and its many legend items, we used a map frame that has a margin to the right. This methodology allows us to get a large amount of important information into the map without directly sacrificing a large area of the map itself.
Titles, scale bars, sourcing, and legends are the final touches that we add to a map. This process is critically important when mapping healthcare patients, hospitals, service areas, and all the data that comes with them. If a map does not give the reader the information needed to understand what the map is displaying, the cartographer behind it has fundamentally failed their job. At Stratasan, we take our GIS and cartographic responsibilities seriously. The maps we make must be maps that our customer can read and comprehend quickly and easily. Without using these principles, our maps would not be as effective and informative as they are today.
Article by Jason Haley, GIS Manager for Stratasan.