PBDS is a test used by hospitals to assess the critical thinking and skills of travelers. I personally took the test and it is geared towards doctors (for example--what tests would you ORDER for the patient) and required detailed explanations (saying 'drawing labs' is unacceptable, you must say the name of the test). I was not told about it until the day my assignment started and failed as well as some of my co-workers. If you decide to take an assignment be sure to ask potential interviewers, because some agencies will not reimburse you for time spent or mileage to take test. I hope this helps and good luck!