Have you gotten the error “All fields must be aggregate or constant when using table calculation functions or fields from multiple data sources” in Tableau?
Complex data questions are hard to answer with simple visuals. When questions have multiple components, a single graph may not be enough. For instance, imagine you have a table of data displaying average daily high temperatures by month that looks like this:
As you likely know from using Table Calculations in Tableau, they only compute against the marks displayed in a worksheet. Check out this webinar in you need a refresher.
That means when a filter is applied to the worksheet, a table calculation will update to reflect only the data present in the worksheet.
You may have noticed that under “Compute Using” in the Table Calculation dialogue box there is a section called “Specific Dimensions” where you would normally select a scope and direction. You generally only need to use Specific Dimensions when you have 3 or more dimensions in the view.
Take a graph like the following:
Let’s say you want to visually distinguish the 5 days with the lowest profit ratio. I’ll show you how I prefer to approach situations like this.
I shared an example with a class recently about how to use Table Calculations in Tableau and got a request to share this via a write-up. One of the most powerful things about Table Calculations in Tableau is the ability to set a scope and direction.
When calculating growth rates from one date period to another, it’s important to compare apples to apples. For instance, when building a graph in Tableau to compare quarterly sunscreen sales in Seattle, I probably wouldn’t want to compare Q3 Sales (July - September) to Q2 Sales (April - June) because there will be more sales in Q3. The product has a cyclical sales cycle. Instead, I would rather compare Q3 Sales of this year to Q3 Sales of last year to more accurately understand growth rates.