What is the Merimekko calculation actually doing?

Table calcs have ALWAYS been my biggest weakness in Tableau. I find them incredibly difficult to understand and finding a plain language way of explaining them has always been tough. If I heard the words addressing and partitioning, they might as well have been speaking Swahili.

I'll have a more detailed blog coming soon on how I've learned to explain table calculations; I had a serious lightbulb go off Friday morning while I was teaching. In the meantime, I thought I'd look back at this week's Workout Wednesday and explain what the calculation for the columns is actually doing.

First up, here's the final viz:

The trickiest piece for me was understanding how the width of the bars worked. Here's the calculation we'll review:

Notice that I named the calculation "Columns". I do this when I know I need a calculation to be placed on a specific shelf. It's a way that I remind myself. When I choose "Edit Table Calculation" I'm presented with this view.


This setup tells me that for each Sub-type (i.e., gender in this case), calculate the Columns formula by Job Type. Ok, got it? Got it! Let's look back at the formula and explain what is actually being calculated.

Note: The Job Types are sorted by the % of female in descending order.


Hopefully this helps explain a bit about how the calcs work to get the bar widths correct in a Merimekko. I know it helped me think through it.

How might you explain it differently?