What is a secondary dimension?
Take a look at the image below. It's showing a metric (in this case sessions) and a dimension (in this case date).
But what if you want to split up that information even further, for example, to see sessions split by gender?
That's where secondary dimensions come in: In this example, gender is the secondary dimension.
Here's what the same "sessions" data looks like when we've chosen "gender" as a secondary dimension.
You still see sessions by date, but the extra dimension (gender) gives more detail to the chart.
Adding a secondary dimension
Secondary dimensions are available for many of our line charts and column charts, for both reports and custom dashboards.
Then, open the widget's settings by clicking "..." at the top right of the widget, then select "Edit".
If your metric supports secondary dimensions, you'll find this option in the widget's settings. Choose your secondary dimension from the drop-down options, and click "Save Settings".
If you have a line chart, you'll see multiple lines on the chart for your secondary dimension.
If you have a column chart, you'll see extra columns in the chart for your secondary dimension.
Stacked column charts
By default, secondary dimensions are shown as extra side-by-side columns in column chart widgets (like in the Google Rankings widget above).
However, you can also "stack" them.
To do this, open the column widget's settings and change the "Stacked Columns" option to "Yes".
When stacked, the secondary dimension will appear as a different color in each column (rather than as side-by-side columns).