population
Statistics
Microbiology
Sociology
Psychology
A complete group of individuals or things that research aims to describe.
Examples of population in the following topics:

Populations
 This is one type of population.
 A statistical population is a set of entities from which statistical inferences are to be drawn, often based on a random sample taken from the population.
 This type of information gathering over a whole population is called a census .
 A subset of a population is called a subpopulation.
 If different subpopulations have different properties, so that the overall population is heterogeneous, the properties and responses of the overall population can often be better understood if the population is first separated into distinct subpopulations.

Summary of Types of Hypothesis Tests
 Populations are independent and population standard deviations are known (not likely).

DensityDependent and DensityIndependent Population Regulation
 Population regulation is a densitydependent process, meaning that population growth rates are regulated by the density of a population.
 In population ecology, densitydependent processes occur when population growth rates are regulated by the density of a population.
 Usually, the denser a population is, the greater its mortality rate.
 A dense population that is reduced in a densityindependent manner by some environmental factor(s) will be able to recover differently than would a sparse population.
 In this population of roundworms, fecundity (number of eggs) decreases with population density.

The Future of Population and Urbanization

Student Learning Outcomes
 Conduct and interpret hypothesis tests for a single population mean, population standard deviation known.
 Conduct and interpret hypothesis tests for a single population mean, population standard deviation unknown.

Student Learning Outcomes
 Conduct and interpret hypothesis tests for two population means, population standard deviations known.
 Conduct and interpret hypothesis tests for two population means, population standard deviations unknown.

Population Growth
 Population growth can be modeled by an exponential equation.
 ${\Delta}P$ denotes the change in population.
 It is the Population Growth Rate ($PGR$).
 A positive growth rate indicates an increasing population size, while a negative growth rate is characteristic of a decreasing population.
 A growth rate of 0 means stagnation in population size.

Population Genetics
 Population genetics is the study of the distributions and changes of allele frequency in a population.
 Population genetics is the study of how selective forces change a population through changes in allele and genotypic frequencies.
 In population genetics, the term evolution is defined as a change in the frequency of an allele in a population.
 When a small number of individuals become the basis of a new population, this new population can be very different genetically from the original population if the founders are not representative of the original.
 Define a population gene pool and explain how the size of the gene pool can affect the evolutionary success of a population

Population Size and Density
 Population size and density are the two most important statistics scientists use to describe and understand populations.
 For example, a larger population may be more stable than a smaller population.
 Analyses of sample data enable scientists to infer population size and population density about the entire population.
 A variety of methods can be used to sample populations.
 Choose the appropriate method to sample a population, given features of the organisms in that population

Global Aging Trends
 Globally, most countries are seeing the average life expectancy of their populations increase.
 The varied life expectancies and younger populations are illustrated in the map below, which depicts the percentage of each country's population that is over 65.
 It is pretty clear from the map that more developed countries have much older populations and a greater percentage of their population is aged 65+.
 More developed countries have older populations as their citizens live longer.
 Less developed countries have much younger populations.