ABSTRACT
This chapter introduces estimating population size, under the assumption that the population is closed. The US Census Bureau tries to enumerate everyone in the decennial census. Inevitably, however, persons are missed, leading population estimates from the census to underestimate the true population count. As Congressional Representatives, billions of dollars of federal funding, and other resources are apportioned based on census results, it is important that the population counts be accurate. Separate population estimates are derived for each poststratum, where the population is poststratified by region, race, ownership of dwelling unit, age, and other variables. The P-sample is taken directly from the population, independently of the census, and is used to estimate number of persons missed by the census. Multiple samples from a population may be used to estimate its size. In the simplest form, two independent simple random sample (SRS)are taken and the number of population units found in both SRSs is used to estimate the population size.
