a computer system in which resources are selected or purged based on extremes of utilization effectively handles newly added resources whose initial utilization rankings do not reflect their true popularity . new resources are arbitrarily assigned an initial utilization ranking that is in the middle of the range of utilization rankings -- e . g ., preferably the median or , more preferably , the mean -- of other members of the group . therefore , the new resource is not immediately either selected or purged , because its initial utilization ranking is not at either extreme , and eventually , after not too long an interval , the utilization ranking reflects the true conditions , and the resource will be selected or purged , or not , as the statistics may warrant . in the meantime , other resources in the group are selected or purged based on their actual statistics which reflect the true conditions closely enough .