This project looks a bit more at how many people are earning the federal minimum wage or less across the United States. The Bureau of Labor Statistics compiles a report each year (Links to an external site.) on the characteristics of people earning minimum wage. This report is typically widely covered because it provides a snapshot of low-income earners across the country. Most major changes in minimum wage policy are now being handled at the state and local level (Links to an external site.), rather than at a national level. In your writeup, be sure to discuss how your state differs in minimum wage laws relative to the federal level. Some states, like California and Washington, have a lot of local minimum wage laws, while other states just default to the federal level. This project will ask you to do some independent research on your own state.
We'll use data from the BLS to look at the percentage of workers who earn at or below the federal minimum wage, not their state's individual minimum wage. Working below the federal minimum wage is not reserved just for people who earn tips. Listen to this brief NPR podcas (Links to an external site.)t on "subminimum wage" payments. Because it's at the federal level, it will make states with higher minimum wages look like they're doing better than others.
Finally, you'll want to use MIT's Living Wage Calculator (Links to an external site.) to see how the minimum wage differs from the living wage for your state as a whole. The site provides a county-level and metro-level look at what would be considered a living wage and a poverty wage. On each state page, however, you can see the results for your state as a whole. If any of the cities in your state have increased minimum wage above the federal level, you'll be able to use this calculator to see if the adjustment turns their minimum wage into a living wage.
Data Sources
Bureau of Labor Statistics (2018). "2019/W3: How many people earned the Federal minimum wage? (Links to an external site.)" via Andy Kriebel (Links to an external site.).
Chambers, Matt (2015). Inverted Hexagon Shape File.
Taylor, Kevin. (2017). Hex Map Plot Coordinates Excel File.
Here's What to Do
Read through the Pew Report, NPR Article, and BLS Minimum Wage release linked above to frame the purpose of this project. You'll be visualizing minimum wage data from 2002 to 2017 to show how these values differ across the country and over time. Be sure to summarize these three articles in your writeup and discuss how your state differs, if it does, from federal policies.
The focus of this project will be to show you three different ways that you could visualize time series data. While we traditionally think of line charts as being the only method, Tableau has other neat ways of representing time dimensions.
Data Sheets
Create a new folder for this project and save all of the files for this project. For the Inverted Hexagon Shape File, you'll need to save that image in your shapes folder located in your "My Tableau Repository" folder on your computer's system. This will be used to help make a hex map for your last visualization. To open your Repository folder, open Tableau, select File from the main menu and then select Repository Location. Save the hex file, in the shapes folder.
Connect your Hex coordinates file and your BLS data file using the State field in both sheets.
Tableau Work
Your dashboard for this project will include a heat table (Links to an external site.), a hex map (Links to an external site.), and a stacked area chart (Links to an external site.). We'll use actions to make sure that the visualizations interact with each other. It's helpful to be aware now that the stacked area chart will look different when you upload it to Tableau Public than when you make it on the dashboard.
Visualization #1: Heat Table
We'll start by creating a variation of a table you read about in the first chapter of How Charts Lie during your Week 2 readings (on page 23 of the PDF). Start a new worksheet and title it Heatmap. Change your year dimension to represent a date instead of a number. Add the Year dimension to the columns shelf and place the State dimension on the Rows shelf. Select text table from the Show Me tab to convert this into a table. Place the Total measure in the Color Marks card.
The "Total, 16 Years and Over" entry is for the whole United States. Rename this to "Entire United States" by editing the alias. Hide this from the state table, but don't exclude it from the data. We'll use this for our third visualization.
There are two approaches to formatting the year column labels to help make them easier to read. You could format the labels to be rotated sideways or you could format the number to be a custom number of 'YY. The example image I've linked above does both just so you can have an idea of what you like. It's up to you what you think looks better.
You may want to edit the names of individual states using the "Edit Alias" feature to make the names shorter. For example, you could change North Carolina to N. Carolina. If you prefer to use the abbreviations for the states instead of the full name, you can place the Abbreviations dimension on the Rows shelf instead of State. If you decide to use Abbreviations, add the State measure to your detail marks card and to the tooltip marks card so you can use the state name in the tooltip and for your actions to work later.
Be sure to update the features of your data visualization to ensure they look good, including:
• Rename your sheet table in the bottom toolbar
• Remove unnecessary header labels in the table
• Add a title to describe your visualization
• Select a color scheme that's different than the default
• Format your measures to be in percentages instead of decimals
• Change the range of your color scheme to run from 0 to 10%
• Update the tooltip to be more informative and remove any unnecessary information
Visualization #2: Hex Map
The first visualization helps us see how the percentage of workers earning the federal minimum wage changes over time by just using colors rather than values. We can use the Pages feature in Tableau to see the country transform over time. This tool can be used to create animated graphs, but that animation doesn't transfer well to Tableau Public. We'll use the Pages feature, which is similar to how a filter works.
One of the issues with the data visualizations and maps is what's sometimes referred to as the Alaska Effect: Alaska is really, really BIG. Not only is Alaska big—more than twice as large as the next largest state, Texas—but the Earth is round. And when we try to present a round object on a 2D screen, the landmasses near the poles, i.e. Alaska, will appear larger than they actually should. Due to the size of Alaska, in addition to its relative lack of proximity to the “lower 48”, including geographical precision can be costly when it comes to delivering your message. This is where a hex map can be really valuable. You'll create a hex map of the United States and color the states based on the percentage of people at or below the minimum wage for each year.
Create a new worksheet and add your mapping coordinates by right-dragging the Column measure to the columns shelf and the Row measure to the rows shelf. Change both aggregation levels to average instead of sums. Drag the Abbreviation dimension to Label marks card. Notice that it appears our states are aligned upside down? This is due to the coordinates from our file where the states in the north had a lower value than those in the south. To correct this, edit the vertical axis and reverse it.
Change the default “circle” to our “inverted hexagon” custom shape by changing Marks type to “shape” then click shape > more shapes > go to wherever you have saved your hexagon .png or earlier. Adjust the size of your hexagons manually until they form a honeycomb shape. You will want to minimize the amount of whitespace between states, but not so much that there's no apparent border between the hexagons. Don't worry too much about the worksheet view because you'll adjust the shapes later for your dashboard.
Set the color mark using the Total measure. For now it's showing a sum of the values instead of each state. Drag the Year dimension to the Pages card so that you can click through year-by-year and see how the states changes their value over time. You'll adjust the features of this below in the formatting section.
Clean up the map a bit by updating the Label mark and change the alignment to center for both horizontal and vertical alignment. Set the font to bold and check the box to allow labels to overlap. Remove all grid lines, remove the zero line, unshow headers, and resize accordingly.
Update the features of your visualization to ensure they are presentable for the dashboard:
• Rename your sheet tab in the bottom toolbar
• Update the color scale to match the color scheme you selected on the first visualization. Be sure to change the ranges to match the previous one.
• Update the tooltip to be more informative and remove unnecessary information (like the column/row values)
• Add the State dimension to the tooltip so that you have the state name instead of the abbreviation in the tooltip. Be sure that it is in the details mark card as well.
• Update the Year Card to have a more presentable title. Change the customization features to remove the history control option. The playback feature is nice, but it actually doesn't work on Tableau Public, so you can remove the ability to play the map if you want.
Visualization #3: Stacked Area Chart
A third way to visualize time series data is by using line charts, which we've looked at in the previous projects. Because the data is often reported as the percentage of people "at or below" the federal level, we can use area charts to represent this collection of people, but break down that measure to show the differences. A stacked chart allows us to see a cumulative total of multiple measures.
On a new worksheet, place your Year dimension on the columns shelf and drag the At Minimum Wage and Below Minimum Wage measures to the row shelf. This will initially create two separate line charts. Drag the lower line chart by the vertical axis and place it over the other vertical axis to combine them into a stacked line chart showing the total percentage of people at or below the federal minimum wage. Change the marks card from automatic to area. Drag the Measure Names dimension to the Color marks card and drag another copy of it to the Label marks card to label the areas.
Your chart is showing a sum of each state's percentage, which is why the vertical axis values are so large. Drag the State dimension to the filter card and select use all. Right-click on the state filter and select show filter to include a card on the right side of the window. It will initially show all states selected, but edit the filter to show a single value drop-down list. Select your United States option that you renamed earlier in the first visualization. When we put this together on the dashboard, a visitor will be able to change the view to match the state they select in the other visualizations. In the customize section of the filter card, remove the option to show "All" Value
You'll notice a large spike around the time of the Great Recession, but we want to add a reference band as we did on the first project to indicate that was a recession. Be sure to provide a label for this recession either as a tooltip item or as a label on the chart.
Lastly, let's show all the data in the tooltip to see what happens each year. Drag the State, Total, At Minimum Wage, and Below Minimum Wage measures to the tooltip box. Be sure to edit and arrange your tooltip in the section below to order these in a logical way.
Update the features of your data visualization to ensure they look good, including:
• Rename your worksheet table in the bottom toolbar
• Format your measures to be as percentages instead of decimals
• Add a title to describe your visualization
• Select a color scheme that's different than the default and your other visualizations
• Sort the measure names by size so that the large measure is on the bottom
• Update the axis labels to be more appropriate
• Edit your horizontal axis to remove whitespace on ends of the chart
• Update the legend card title to be more presentable
• Update the tooltip to be more informative
• Remove the labels card since you already labeled the chart.
Putting it All Together in a Dashboard
Create a New Dashboard and be sure to label the tab. Set your dashboard size to be a fixed size that matches "Letter Portrait" (850 x 1100) so that it looks like the dimension of a sheet of paper. The dashboard is your opportunity to arrange your visualizations before sharing them publicly. Sketch where you think each visualization should be placed and use vertical/horizontal tiles to help arrange things. Use the "objects" pane on the left side to arrange pieces to tell a story. For each project, review Tableau's Best Practices for Effective Dashboards. Be cognizant of where your legends and tools are on the dashboard. Make sure they are close to the appropriate visualization.
On your dashboard, be sure that you have the drop-down list to select a state for the stacked area chart and also the slider/dropdown card for the year on the hex map. Once we add actions to the dashboard, you'll be able to interact with the visualizations.
Action Items
For this dashboard, we're going to link your visualizations across states. It's important that you have the State measure in each visualization. If you're using abbreviations instead of state names, all you have to do is add the State measure to the detail marks card and it will be included. After you've arranged your dashboard, add actions by going to the main menu and selecting select Dashboard then Actions. Add the following actions:
Action Action Name Source Sheets on Dashboard Run action on: Target Sheets on Dashboard Clearing selection will: Target Fields
Highlight State Highlighting Heat Table and Hex Map Select Heat Table and Hex Map N/A State/Abbreviation
Filter Stacked Update Heat Table and Hex Map Select Stacked Area Chart Leave the filter State
Be sure your dashboard has at least the following items:
• A clear, distinct title
• A description of fewer than 300 words
• Each of the 3 visualizations you made
• Highlight tools and legends to make your work interactive
• A separate note of the source of your data file
Each visualization should be fitted to their tiles. This can be done by clicking on "More Options" within each visualization and selecting "Fit > Entire View." Make sure there aren't scroll bars on your dashboard! When you're done, you will need to export your dashboard as an image to include in your PDF submission. Select "Dashboard" from the menu and then "Export Image" to save the dashboard as a .png file.
Ready to publish it online?
Before you can publish your dashboard to your Tableau Public profile, you need to extract your data by going to "Data" in the menu bar, selecting the title of your sheet, and then "Extract Data" for each data file. Save this data extraction with your other project files. To publish your dashboard to your Tableau Public account, select "Server" from the menu, then Tableau Public, and finally select "Save to Tableau Public." When your Tableau Public account opens, be sure to have your dashboard public. If you make changes to your Dashboard, you can republish it to your Public profile, and it'll update for you and maintain the link.
When you're ready to submit your dashboard for peer review, go to your Tableau Public version of your dashboard and select the sharing icon in the bottom corner of your visualization. Use this link to submit your dashboard for peer review for grading. 50% of your project grade comes from peer reviews completed by your classmates and 10% of your project scores come from peer-reviewing your classmates.
If you share your Dashboards on any social media accounts (Twitter/FB/IG), please tag me (@Wootenomics). I'm happy to share your work with my followers.
Write Up
You have three pages to summarize any of your visualizations, any articles listed above, and the data you worked with to create your visualizations. Be sure to clearly define the variables and measures you used in your visualizations and provide some connection to the course material we've covered this semester. If there are questions listed above, be sure to answer them in your write-up. You should be using in-text citations and include a full set of references for data, articles, and any additional work you include.
Appendix Material
In the appendix (the section after your analysis), include a reference page that lists your references in APA format and an exported image of your Tableau dashboard. Your entire file should be saved as one single PDF and uploaded to Canvas.
Here's the order:
• 3-page analysis
• Reference page
• Dashboard image export
Ready to Submit Your Project?
To submit your project, do the following:
- Publish your data visualization to your Tableau Public profile.
- Submit the link to your completed dashboard for Peer Review
- Submit your final PDF to Canvas
Peer Grading
Part of the learning process is to evaluate other students on their organization, presentation, and accuracy of the same dashboard you just completed. Your role as the peer grader is anonymous to the other students you are grading. By providing honest feedback, you can help improve not only their projects but your future ones as well. You will only grade their dashboard not their written paper. Your review should be based on the quality of the work, not on whether they completed the work. I need you to be critical. Find areas they can improve.
You'll learn two skills in the process: providing feedback to others and self-analysis of your own work. You will be assigned to peer review 5 dashboards through Canvas. I will provide a rubric to judge the quality of work they have submitted. A portion of your final grade will come from the quality of your peer reviews. You can see the list of other students you've been assigned to review for this project by going to the dashboard submission page.
Your overall project grade is based on your written analysis, the median score your receive from your peers, and the completion of peer grading. Each peer review you complete will be worth 2% of your project (up to 10% of your grade). 40% of each project score is based on the median score you receive from your peers. The last 50% of your project score is based on your written analysis.
We will verify your peer grading through two methods. I will randomly select 15 students for each project and evaluate your ability to provide accurate reviews and constructive feedback. Second, as my TA calculates the median score for projects, they will alert me if your score deviates too much from the other peer reviews a student receives. Your role as a peer grader is anonymous, so I expect you to provide honest feedback to help others. If you are found to be inflating grades or shirking on the peer grading portion, you will not receive credit for any peer reviews you complete on that project.