Median Household Income by State - 1984 to 2016

Week 13 Viz

Posted by David Velleca on June 1, 2018

Data Storytelling and Data Viz Approach

This dataset is well suited to looking at the data both geographically and as a trend over time. In an attempt to accomplish this in a single viz, I created a tile map, where each state is represented in its approximate geographic location by a line chart that shows the trend. The process to create this type of map is similar to building a hex map, and requires a supplemental data source.

The supplemental data source is exceedingly simple, with just four columns (though you could get away with three) - State, State Abbreviation, Column and Row. I've uploaded a copy of the file here if you're interested. Using this file, and the original CSV dataset, you can join on State (note that the original DS has D.C., where the supplemental dataset has it as Washington D.C.). To get around this, I used Tableau Prep to clean, normalize and join the data, but could have simply modified one of the files.

Once you have the data in Tableau, you can drag [Column] and [Row] to their respective shelf as the absolute numbers (no aggregation), and edit the Y axis - [Row] - to set the scale to reversed. Then construct your viz as you wish. I used [Year] on the Columns shelf, and {Median Income} on the rows. Once you're here, you'll need to right click on the [Column] and [Row] pills and set them to discrete. This will leave you with a line graph per state in the tile layout. You can clean it up by hiding the headers and axes.

Having built my tile map, I chose to use parameters to drive some interactivity. First, I created start and end year parameters that with a calculated field filter the viz to the desired time period. Second, I chose to offer two different views of the data. One that compated the states' median incomes to the United States' median income, the other looked at the overall trend of the data for the selected time period. The parameter drove a calculation that either showed the U.S. Median Income or nothing, and another that allowed for coloring based on the user's choice. To wrap it all up, I created one final calculation driven by the parameter to provide some information on the chosen view.

Overall, this is a pretty simple viz with only two views - the tile map, and the dynamic text.

Data Source

The dataset this week was sourced from the U.S. Census Bureau. Please be sure to cite the source on your viz.