In Summit, you can use existing contextual Student Data fields to build a custom group of students, for example female high prior attainers. Our standard contextual fields include the following: Gender, Disadvantage, Ethnicity, SEND, EAL and Prior Attainment. You can also create your own custom fields, please see this article for further details: Summit Custom Columns

To create your Custom Comparison group, click into Group Setup Management and go to Analysis Setup.

Then click into the Analysis Setup tab, and select Custom Comparisons. 

In the Custom Comparisons page, click Add a Group.

This will open a pop-up where you can name your comparison group, and select the fields you wish to include in the Comparison Type drop down. Each field you add will appear on the right side of the window. Once you've made you selection, press Add Group.

Your comparison will appear in the list and then you can press Save Comparisons to finish.