Effective January 1, 2001, the annual salary of the President of the United States was increased to $400,000 per year, including a $50,000 expense allowance.he president's salary is set by Congress, and under Article II, Section 1 of the United States Constitution, may not be increased or reduced during his or her current term of office.
As such, stratification is the relative social position of persons within a social group, category, geographic region, or social unit.
Stratification is the process of dividing members of the population into homogeneous subgroups before sampling. The strata should be mutually exclusive: every element in the population must be assigned to only one stratum. The strata should also be collectively exhaustive: no population element can be excluded. Then simple random sampling or systematic sampling is applied within each stratum. This often improves the representativeness of the sample by reducing sampling error. It can produce a weighted mean that has less variability than the arithmetic mean of a simple random sample of the population. In computational statistics, stratified sampling is a method of variance reduction when Monte Carlo methods are used to estimate population statistics from a known population.