Periodicity hypotheses for various global events over the past ∼250 m.y. are reevaluated following rigorous inspection of the radiometric data base utilized therein. I suggest that these periodicities of ∼26 to ∼33 m.y. result from subjective use of radiometric data in the literature. Further search for periodicity in global events, especially those involving mathematical analysis of data from the geologic time scale, should be postponed until an adequate data base of high-quality radiometric ages for Phanerozoic time becomes available.