Source: U. S. Census Bureau, American Community Survey, 5-Year Estimates. Updated every year. http://factfinder2.census.gov
A household includes all the persons who occupy a housing unit as their usual place of residence. A housing unit is a house, an apartment, a mobile home, a group of rooms, or a single room that is occupied (or if vacant, is intended for occupancy) as separate living quarters. Separate living quarters are those in which the occupants live and eat separately from any other persons in the building and which have direct access from outside the building or through a common hall. The occupants may be a single family, one person living alone, two or more families living together, or any other group of related or unrelated persons who share living arrangements. (People not living in households are classified as living in group quarters.)Persons per household, or average household size, is obtained by dividing the number of persons in households by the number of households (or householders).
Scope and Methodology:
These data are collected in the American Community Survey (ACS). The data for each geographic area are presented together with margins of error at factfinder2.census.gov. The data are period estimates, that is, they represent the characteristics of the population over a specific 60-month data collection period.
Margins of Error (MOE). ACS estimates are based on a sample and are subject to sampling variability.
The degree of uncertainty for an estimate arising from sampling variability is represented through the use of a MOE.
The MOE used with ACS estimates can be interpreted as providing a 90 percent probability that the interval defined by
the estimate plus the MOE and the estimate minus the MOE (the upper and lower confidence bounds)
For example, suppose the 5-year ACS reported the percentage of people 25 years and older in Birmingham, Alabama who had a bachelor's degree was 21.3 percent and that the MOE associated with this estimate is plus or minus (+/-) 0.9 percent. By adding and subtracting the MOE from the estimate, we can calculate the 90-percent confidence interval for this estimate at 21.3%, +/-0.9%:
Therefore, we can be 90 percent confident that the percent of the population in Birmingham, Alabama of age 25 years and older having a bachelor's degree in 2007-2011 falls somewhere between 20.4 percent and 22.2 percent.
For this Fact and other 5-year Social Characteristic Facts (listed below), their estimates and margins of errors or percents and percent margins of error can be found on Data Profile - Social Characteristics. This profile is displayed by geography. Click on the link for "Browse data sets for (geography picked)" near the top of the Quick facts profile page, click on the link for People QuickLinks/American Community Survey - "Social Characteristics" for the data profile.