Use of a repertory grid is a method for finding out how people look at the factors they use in making judgments about differences between things. For example, in interviews about client satisfaction, you could use a repertory grid to separate out attributes that clients value. This came from Practical Management Consultancy by Calvert Markham (pg. 145). For example, ask clients:
Think about the lawyer or lawyers who give you the best service and the worst service. Imagine them standing side by side and tell me about the differences between them in terms of what they do.
A repertory grid could help elicit differences in performance between two law firms. It could help draw out difference people perceive between two structural choices in a law department, as when a department is considering designing single points of contact for key business units.