We can query on constituents that attended a certain program category by creating a Constituent's query that has filters for the program category
  1. Click Analysis > Information Library > add an ad hoc query
  2. Choose the Constituents source view
  3. Under the browse for fields in column expand Sales Order > then expand sales order item > then expand sales order item ticket > then click on Program
  4. Drag Category from the middle column to the Include records where section
  5.  User-added image