It’s Community month for #WOW2022, and so guest poster Collin Smith set this challenge to get us all thinking about how to make an accessible dashboard. There were 3 tiers of requirements, so lets start with Tier 1.

Building the charts

I used 5 sheets to create the core of this viz. One for the KPI title, 1 for each KPI and 1 for the bar chart. Typically I would have tried to build the KPI section all on a single sheet, but when I interacted with the solution to get a feel for how the tabbing worked (and given the hint in the requirements, not to use more than 5 sheets), I figured it would be necessary.

First up we need to define a parameter to use for the data selector. For this I created

Order Date Week

DATE(DATETRUNC(‘week’, [Order Date]))

and then adjusted the default sort order of the new field to be descending (right click pill -> default properties -> sort)

I then created the parameter to reference this

pSelectedWeek

date parameter where the values were added from the Order Date Week field. Default value set to 09 Aug 2021 (the data set didn’t match whatever Collin had used as my data went from 2018-2021, so I used a week in 2021 which was about equivalent to the week Collin had used, 10 Aug 2020).

The default sort on the field applied above, meant the dates got added in descending order.

I then created a field to filter the KPI charts

Is Selected Week?

[Order Date Week]=[pSelectedWeek]

this returns true or false.

On a new sheet, add Is Selected Week? to Filter and set to true. Then add Region to Filter and select East, West and South. Set the mark type to Polygon. Click the Tooltip button and clear the Show Tooltips option. Update the Title of the sheet as below, referencing pSelectedWeek and Region. Use Verdana 16 pt.

On a new sheet, again add Is Selected Week? to Filter and set to true. Then add Region to Filter and select East, West and South. Set the mark type to Polygon. Click the Tooltip button and clear the Show Tooltips option. Adjust the properties of the Sales field so it is formatted to $ with 0dp, then add Sales to the Detail shelf. Edit the title of the sheet to be where the word Sales is Verdana 16pt and the referenced Sales field is Verdana 32 pt. Note – this isn’t how I originally built this KPI, but I had to modify my approach to allow the screen reader to be able to read the values out (requirement Tier 3).

Repeat this process on a new sheet for the Profit KPI. And the similarly for the Profit Ratio KPI (note you’ll need to create the field first

Profit Ratio

SUM([Profit])/SUM([Sales])

and format to % to 1 dp.

To build the bar chart, we need a parameter to drive the metric selection.

pSelectMetric

I used an integer data type and assigned 1 to Sales and 2 to Profit, defaulted to 2.

From this I could create

Metris to Show

CASE [pSelectMetric]
WHEN 1 THEN [Sales]
WHEN 2 THEN [Profit]
END

On a new sheet I then again added Is Selected Week? to Filter (true) and Region to Filter (East, South, West). Then I added Product Name to Rows and Metric To Show to Columns and sorted by Metric To Show descending.

I then add Product Name to Filter and filtered by the Top 10 Metric To Show

Initially this may make everything disappear, but don’t panic. Click on the Is Selected Week? and Region fields in the Filter shelf and Add to Context.

All of our sheets have 2 filters in common and we need to ensure they’re all working together. So now click on the Is Selected Week? filter and Apply to Worksheets > Selected Worksheets and select the 4 KPIS sheets you’ve built. Repat this with the Region filter. Only the bar chart should have the additional Product Name filter.

Now we need to format the look of the bar chart.

• Add Profit Ratio to Colour
• Add Metric To Show and Profit Ratio to Label. Format the label as below to Verdana 10pt.

• Make each row a bit wider
• Format the Product Name header for each row to be Verdana 12 pt.
• Make the Product Name column a little wider
• Add a dotted Row Divider to the Header level only

• Add a thick black line to the Axis Ruler of the Rows

• Hide the Metric To Show axis
• Hide the Product Name column label (right click > hide field labels for rows)
• Set Axis Ruler for Columns to None
• Update the Tooltip using a mix of Verdana 16pt and 12pt

It should be looking something like…

Next, we need to give a title above the bar chart, which needs to be dynamic based on the metric selected. Create

Axis Label

CASE [pSelectMetric]
WHEN 1 THEN ‘Sales | Profit ratio’
WHEN 2 THEN ‘Profit | Profit ratio’
END

Add this to Columns.

Now to add the title. For this we need the name of the top Product Name. We need a new field for this

Top Product

WINDOW_MAX(IF SUM([Metric To Show]) = WINDOW_MAX(SUM([Metric To Show])) THEN MIN([Product Name]) END)

Let’s dissect this… WINDOW_MAX(SUM([Metric To Show])) returns the largest (maximum) value of Metric To Show that is being displayed. So we then test to find the row that has this value, and when a match is found we return the Product Name. This means we’ll get the Product Name for the first row of data, and NULL for the rest. The outer WINDOW_MAX is then finding the max value of the Product Name or Null, which again will be Product Name, and this value is then ‘spread’ across all rows. This means we have a single value for the top Product Name stored against every row, so when we reference it in the title we only have one value.

Add Top Product to Detail, then update the title as below using a mix of Verdana 16pt and 12 pt.

Finally, add the caption (Worksheet -> Add Caption) and adjust the text to match the required wording, referencing fields/parameters where appropriate.

Building the Dashboard and setting Focus (Tier 2)

Using a mixture of horizontal and vertical containers, I added all the necessary objects to the dashboard. I added the title and subtitle in a text box using a mix of Verdana 32pt and 16pt. I updated the titles and of format of the parameters and filters to use Verdana 12pt, and I added my standard footer. I then read through the community post Collin had provided to get an understanding on how to set the focus. As a result, I renamed all my containers and objects in the Item hierarchy.

Based on Collin’s viz, I needed to define the order of focus as

• Filter-Week
• Filter-Region
• Filter-Metric
• View-KPI Title
• View-SalesKPI
• View-ProfitKPI
• View-ProfitRatioKPI
• View-Bar

As per the instructions, this was going to require an edit to the XML of the workbook. So I did as advised and saved a copy of my workbook so I had a backup in case it all went wrong.

I then made a note on a piece of paper of each of the above fields and assigned a unique number against it ie Filter-Week 10, Filter-Region 20 etc.

I then opened up Notepad++ and opened the twb file in the editor.

I searched for dashboard and found the tag mentioned in the article and changed the relevant property to false

I then searched for zone, and went through changing the ID of every <zone> section. Anything that wasn’t part of my list above, I set to a unique sequential number from 100. When I hit one of the zones above, I set the value to the number I’d written down on paper. Once done I saved the file, closed notepad and reopened the workbook in Desktop. It loaded – phew! I then published to Tableau Public to test the tabbing functionality and it matched.

Testing the Screen Reader (Tier 3 requirement)

As I use a Windows machine, I used the inbuilt Narrator app. I used it against Collin’s solution to understand what I should expect. and then tested it against mine. Initially mine wouldn’t relay the ‘To open view data pane, click control, shift, enter’ instruction that was explicitly stated. I did some reading up (here) and verified the bar chart allowed the View Data control to show on the tooltip, I loaded the View data window in Desktop, and after publishing made sure the workbook was downloadable. However, I still couldn’t get this information to read out <shrug>. So I messaged Collin – what was I missing? The reply… add the required text in small white font, so it doesn’t display, but can be read! Bah! So simples in the end!

My published viz is here.

Happy vizzin’!

Donna