Abstract: A random selection system for making a select/non-select determination for individual events, such as the arrival of a person or an article, is based on the advanced establishment of a predetermined percentage within the system for carrying out the determinations. The system is particularly useful for security monitoring of employees or passengers passing through workplace exits or through terminal entrances, in that each person processed by the system has an identical probability of being selected for further scrutiny. By presetting the percentage of selections to be applied to all events processed, a degree of security desired by the system operators may be achieved. Both methods and apparatus for electronic random selection are taught. A preferred embodiment of the apparatus utilizes LSI digital circuitry for rapidly carrying out each individual select/non-select determination in response to sensing circuitry which detects the arrival of the person or article being processed.