Measures and Dimensions
Before we build anything in Tableau, it is very important to understand Measures and Dimensions, and how they work, because this is integral to building anything in Tableau.
The Data Pane divides your fields into measures and dimensions. Your visualizations are built off of combinations of measures and dimensions.
Measures are quantitative, numeric variables. We use measures in our visualizations to decide what values we want to see. So the measures here: Profit, Quantity, Sales, these are all our measures that we can work with.
Dimensions are categorical, descriptive variables. So you see here we have structured dimensions like manufacturer, category, product name etc.
Let’s add a measure to the view. I want to examine sales so we’re going to:
- double click Sales.
We could double click or we can manually drag to where we want, but I like double clicking because Tableau generally chooses the right area to put it in.
So here we can see that Tableau automatically “aggregates” measures. The default aggregation is Sum. So right now, we’re only seeing the total sum of sales over everything. This isn’t exactly useful to us, so this is where dimensions come in.
Dimensions help “de-aggregate” or split our measures down into sections. They determine the level of detail that measures are split into. Above, total Sum(Sales) is aggregated to the highest “overall” level. Let’s break down our Sum(Sales) measure.
- double click Category (underneath the Dimensions pane)
Here Tableau split up the total sum of sales into sales by category. And now our measure is aggregated to the level of category detail.
Notice that not all numeric values should be measures. For example, customer ID is purely numeric, but isn’t a measure that can be summed/broken out. It’s actually a dimension. So be careful when working with measures/dimensions.
- double click Sub-Category
We can break it even further into sub-sections.
We should get into the practice of naming our sheets. Let’s name this “Measures vs. Dimensions”.
- Right click the “Sheet 1” tab and click Rename
