1. A method for estimating combined system workloads, said method comprising: obtaining a set of quantile-based workload data pertaining to a plurality of systems; normalizing said quantile-based workload data to compensate for relative measures between data pertaining to different ones of said plurality of systems; determining a confidence interval; using said confidence interval to determine a contention probability specifying a degree of predicted workload contention between said plurality of systems according to at least one probabilistic model; using said contention probability to combine workloads for said plurality of systems; and providing a result indicative of one or more combined workloads.