CAVEATS CONCERNING THE USE OF COMPUTER RANDOM-NUMBER GENERATORS TO SELECT URBAN-TRANSPORTATION SYSTEM EMPLOYEES FOR DRUG TESTS

Federally mandated drug-testing programs for urban transportation syst em employees require routine testing on a random basis. In order to as sure random selection, computer random-number generators often are use d in the process. Unfortunately, some of these generators cannot be re lied upon to produce sequences of numbers which pass even the most fun damental statistical tests for randomness. Consequently, urban transpo rtation system employees chosen for drug testing by using these flawed generators will not have been selected in a manner consistent with fe deral guidelines. Thus, those who use computers in the random selectio n process should ensure that the random-number generators pass two fun damental statistical tests for randomness. These tests are discussed h erein, with application to a particular microcomputer-software combina tion, utilizing a selection of potential seeds. Also, procedures are s uggested which will ensure that an otherwise well-designed testing pro cess will not be tainted by its failure to satisfy fundamental randomn ess requirements.