The ABO used psychometric firms to construct and manage the examinations for them from the mid 1970s to the mid 1990s. American College Testing, Iowa City, Iowa, performed this work from 1980 until 1994, when the ABO took direct control of the oral examination preparation. In 1996, they did the same with the written part. Since then, the ABO has directly prepared, assembled, and conducted the entire examination, relying on psychometric consultants only in an advisory capacity. Two or 3 directors plus some Board staff members and locally hired proctors administer the written examination annually in the fall in 4 widely separated geographic locations such as New York, NY; Atlanta, Ga; Chicago, Ill; and San Francisco, Calif. The ABO directors, assisted by ABO administrative staff and approximately 75 carefully selected senior and guest examiners, administer the oral examination annually in the spring. For logistical reasons, this is administered at a single location, usually Chicago.