Statistical population

The target population refers to the resource to be described. For example, it might be all the registered voters in the United States; or all citizens over the age of 65. It might be the number of fish in a stream network in a particular watershed, the biological condition of streams and rivers in a state, or the habitat condition of streams in a national forest. Critical in developing the design is an explicit definition of the target population. The definition of the target population should contain specific information about the stream network: its spatial extent, its flow status (the perennial network? Includes the intermittent channels?); its size (all stream sizes? Just first order streams?). The definition should be specific enough that an individual could determine whether a location on a stream network is part of the target population; in some cases, membership in the target population might be determined after data have been collected at the site. In statistical usage the term population is applied to any finite or infinite collection of individuals. It has displaced the older term ‘universe’…(ISI).