Using data from various service providers, Tableau provides a powerful feature of overlaying the US census information, such as median household income, population, race, and others. This allows the reader to compare the measure of interest with some demographic information.
Let's use the sample file, Sample – Superstore Sales (Excel). Open a new worksheet and select Sample – Superstore Sales (Excel) as the data source.
Once the data is loaded on the worksheet, perform the following steps to overlay the demographic data:
- Click on the Show Me button to bring the Show Me toolbar on the screen.
- While holding the Ctrl key, click on State and Customer Zip Code from Dimensions and Profit from Measures.
- Click on the symbol of maps on the Show Me toolbar.
- Drag-and-drop State and Customer Zip Code from Dimensions into the Level of Detail box.
- From the main menu toolbar, click on Map and then on Map Options, as shown in the following screenshot:
- From the Map Options (shown in the following screenshot) box, expand the dropdown No Data Layer.
- Select Household Income (median) under US Households.
- From the By: drop-down option, select County to generate a map similar to the one shown in the following screenshot:
Based on our choice of aggregation level for overlaying demographic information, Tableau fills the level (that is, county, state, zip code, and the block group) with the selected demographic information. In our recipe, we are comparing the median household income of counties with the profits generated by each zip code in the data. We can see that there are many counties in Nevada with high median household income, but hardly any profit-generating zip codes. By such comparisons, the reader can identify areas of growth.
Tableau provides these powerful features using various data providers listed on Tableau's website: http://www.tableausoftware.com/mapdata. If these maps do not meet your needs, Tableau also has the option of using an open technology called Web Map Services (WMS) to get the map source. You can read about using a WMS server at http://onlinehelp.tableausoftware.com/current/pro/online/en-us/maps_mapsources_wms.html.