You may contract with OPM or another certified contractor to administer and score OPM tests on a reimbursable basis. If you decide to use a certified contractor, we suggest you look at the "Vendor Criteria List" (see Appendix B). This list provides the types of information you should request from the contractor before entering into a contractual agreement. The Vendor Criteria List in Appendix B is by no means an exhaustive list of questions, it is simply a starting point for you to consider when choosing a contractor to administer and score your written tests.
DEOH, appendix E