The Perfex test is the precursor to the CritiCall test and is being used less and less. There are, however, some agencies that believe this test is an accurate predictor of multi-tasking abilities and continue to use it either on its own or in combination with other multi-tasking tests. The Perfex test is hand-written, and completed by listening to an audio cassette. Only one candidate can be tested at a time and the test must be completed in person. The Perfex test gauges the candidates ability to read map books, write quickly, retain short-term memory, spell, listen, organize information and multi-task.