Median Household Income
The American Community Survey (ACS) has been conducted on an ongoing basis for the entire country since 2005. Annually, calendar-year ACS results are released for areas with a population of at least 65,000. Due to the small sample size, single-year estimates are not available for less-populous areas. Combined estimates for three years of data are available annually for areas with a population of at least 20,000; five years of data are combined for less populous areas. The substantial sampling error present in the ACS is discussed in the data quality comments section below.
The ACS questionnaire asks respondents to supply the income from all sources of each person; the Census Bureau aggregates these figures by household and calculates the median of all households. Annual median household incomes since 2005 are presented on Arizona Indicators for the United States and Arizona, but data for each of the 15 Arizona counties are limited to a five-year average due to the substantial sampling error.
U. S. Department of Commerce, Census Bureau http://factfinder2.census.gov/faces/nav/jsf/pages/index.xhtml. Annual ACS estimates are released in September; five-year averages are available in December.
The Census Bureau publishes the ACS sampling error with every estimate, expressed as the margin of error with 90 percent confidence. The following is an example:
The estimate of the poverty rate in Maricopa County in 2009 was 15.2 percent, with a margin of error of + or – 0.6 percentage points. The interpretation is that there is a 90 percent likelihood that the actual poverty rate was within the confidence interval of 14.6 percent to 15.8 percent. A one-in-ten chance exists that the real rate was outside this range.
For the nation and other very populous areas, the annual ACS estimates are highly accurate. For moderately populous areas such as Arizona, sampling error is moderately large, so caution is urged in using the annual ACS data for the state. The sampling error for less populous areas, such as most of Arizona’s counties, is quite large, even when using five-year averages. Thus, considerable caution is urged in using the five-year ACS data for counties other than Maricopa and Pima.
The published margin of error should be taken into consideration when deciding whether to use a result from the ACS. Whether the reported sampling error is too large depends on the user’s purpose for accessing the data and on the volatility of the measure over time and across geographic areas.In addition to the sampling error, respondents do not always accurately report income and frequently refuse to provide this information.
Median Household Income in Inflation-Adjusted Dollars
Visualization Notes:
Inflation-adjusted median household income fell in 2009, 2010, and 2011 nationally and in Arizona. The decrease over the three years was 12 percent in Arizona, compared to 7 percent nationally. In 2012 and 2013, real median household income hardly changed nationally and in Arizona; Arizona’s figure in 2013 was 7.2 percent less than the national average.
Median Household Income in Inflation-Adjusted (2013) Dollars, 2009-to-2013 Average
Visualization Notes:
The state’s median household income was 5 percent less than the national average between 2009 and 2013. Only in Maricopa County was the median income greater than the national average of $53,046. The median was more than 25 percent below the U.S. figure in Apache, La Paz, Mohave, Navajo, and Santa Cruz counties.
Data Source
U. S. Department of Commerce, Census Bureau http://factfinder2.census.gov/faces/nav/jsf/pages/index.xhtml. Annual ACS estimates are released in September; five-year averages are available in December.
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