Abstract A spike in a set of bioburden data can be considered a bioburden number or numbers that are several times greater in value than the average value of the data set. A spike is not considered a manifestation of a quality issue, but a consistent component of product bioburden that should be taken into account in establishing the minimum acceptable dose in the radiation sterilization process. Rather than a subjective approach, statistical techniques were used to determine when a bioburden number or numbers represent spikes in a set of bioburden data. Bioburden data taken from a cross section of different products over a few months were analyzed. Results of the study identified spikes when the spike bioburden was approximately three or more times the average bioburden for the data set. In those cases where bioburden spikes were identified, use of the spike bioburden rather than the average bioburden increased the sterilization dose by up to 10%.