population

In statistical terms, a population refers to the aggregate of individuals or units from which a sample is drawn, and to which the results of any analysis are to apply-in other words the aggregate of persons or objects under investigation. It is conventional to distinguish the target population (for which the results are required) from the survey population (those actually included in the sampling frame from which the sample is drawn). For practical reasons the two are rarely identical. Even the most complete sampling frames-electoral registers, lists of addresses, or (in the United States) lists of telephone numbers-exclude sizeable categories of the population (who fail to register to vote, are homeless, or do not possess a telephone). Researchers may sometimes deliberately exclude members of the target population from the survey population. For example, it is standard practice to exclude the area north of the Caledonian Canal from the sampling frame for national sample surveys in Great Britain, on the grounds that the Northern Highlands are so thinly populated that interviews in this area would be unacceptably expensive to obtain. However, for most sociological purposes, this particular gap between the target and survey populations is not deemed to be significant-although, in a survey of ‘attitudes to public transportation in thinly populated areas’, it would clearly be problematic. See also statistical inference.