* @param strata_count number of stratas, that is, number of ibfs in the estimator
* @param ibf_size size of each ibf stratum
* @param ibf_hashnum hashnum parameter of each ibf
* @param strata_count number of stratas, that is, number of ibfs in the estimator
* @param ibf_size size of each ibf stratum
* @param ibf_hashnum hashnum parameter of each ibf