I think interviewing altogether is an ineffective way of evaluating people. And the whole process of interviewing and hiring staff members is an outdated, slow bureaucratic way of doing things.

Instead why not work with several people on small projects, ask 5 people to do 2-4 weeks of paid contract work for you and then select the person who was the best fit for longer term work. This tests the real world skills of a person much more effectively than an interview.