Stratified sampling is a method of sampling from a population in statistics. When sub-populations vary considerably, it is advantageous to sample each subpopulation (stratum) independently. Stratification is the process of grouping members of the population into relatively homogeneous subgroups before sampling.tratified sampling is a method of sampling from a population in statistics. When sub-populations vary considerably, it is advantageous to sample each subpopulation (stratum) independently. Stratification is the process of grouping members of the population into relatively homogeneous subgroups before sampling.
Hardening (computing) In computing, hardening is usually the process of securing a system by reducing its surface of vulnerability, which is larger when a system performs more functions; in principle a single-function system is more secure than a multipurpose one.
Hardening - Heating the steel to the hardening temperature and cooling suddenly by quenching in an oil bath. Tempering - Reheating the hardened steel to the tempering temperature in order to relieve stress induced in the hardening process, and remove some of the hardness in exchange for toughness.