Subscribers can draw custom regions on a map to highlight a target area, or generate aggregated data for a specific area of interest. Aggregated data for custom regions can be generated by creating a report of a custom region, or loading a custom region in to a table.
When data for a custom region is aggregated in a report or table, data from smaller geographies within the region is used to calculate the values for the custom region. For drawn and radius custom regions, PolicyMap automatically chooses which type of smaller geographies to use in this calculation based on the data indicator and size of the custom region. Large custom regions may have aggregated data comprised of counties, whereas small custom regions may have aggregated data based on census tracts. Not all indicators have data for all geographies, so in some instances, the geography type will be a less exact fit.
Please note: assembled custom regions aggregate data based on the geographies used to assemble the region, regardless of the region’s size.
When a custom region is opened, the map will zoom to display the entire custom region. The geography type used to aggregated data for a custom region is determined by which zoom level the custom region requires.
The zoom bar on the right shows the numerical scale of zoom levels on the map. The zoom level of 0 is the furthest zoomed out (showing most of the world) and 15 is the furthest zoomed in (showing streets in a neighborhood).
For datasets with the most common geography types (block groups, census tracts, zip codes, counties, and states), the following chart determines which geography is used for custom region data aggregations, according to the zoom level:
- 0-1: State
- 2-4: County
- 5-7: Zip Code
- 8-11: Census Tract
- 12-15: Block Group
In the example on the left, the custom region, in orange, is fairly small, made up a few neighborhoods. The default zoom level for the region is 12, so a report or table using this custom region will aggregate the census tracts highlighted in green.
In this example, the custom region is much larger, encompassing many counties. The default zoom level for this custom region is 6. Therefore, counties (here highlighted in green) are used for aggregations.
To read a full guide on all features on PolicyMap, please look at our Primer available here. If you wanted to know more about a feature or topic, send your request to firstname.lastname@example.org subject "Tutorial Topics".