Santa Barbara, California, used a public opinion survey in conjunction with the update of its general plan to identify issues of particular concern to Hispanic and African-American business people and community leaders. Lancaster County, Pennsylvania, used a visual preference survey to determine physical aspects and patterns that residents preferred and to show how those values could be reflected in an overall plan for the area. Surveys directly involve a relatively small population of a State or region. For surveys with a randomized sample of the population, chosen in a statistically-valid way, the sample can be stratified to include only people within a specific geographic area, income group, or other category of people from whom information is desired. Although it never replicates the overall population precisely, it remains statistically valid.
Respondents provide a composite view of the larger population.
In a scientific, statistically-valid survey, answers are expanded to reflect what the population as a whole might have answered if they had all been asked the survey questions. Informal surveys can never be viewed as the basis for such an expansion. However, large informal surveys can generally indicate the predominant features of public opinion. Public opinion surveys can be led by trained agency staff people. Often, particularly for statistically valid surveys, outside help is appropriate because of the survey's complexity.