Data Dictionary:  ACS 2011 (5Year Estimates) 
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Survey: ACS 2011 (5Year Estimates)
Data Source:  U.S. Census Bureau 
Table:  B19081. Mean Household Income Of Quintiles [6] 
Universe: Universe: Households
Table Details
B19081.  Mean Household Income Of Quintiles  
Universe: Universe: Households  

Relevant Documentation:
Excerpt from:  Social Explorer; U.S. Census Bureau; American Community Survey 20072011 Summary File: Technical Documentation. 
The 20072011 ACS 5Year Summary File Technical Documentation > Appendix A. Supplemental Documentation > Subject Definitions > Population Variables > Income in the Past 12 Months > Mean Income 
Mean income is the amount obtained by dividing the aggregate income of a particular statistical universe by the number of units in that universe. For example, mean household income is obtained by dividing total household income by the total number of households. (The aggregate used to calculate mean income is rounded. For more information, see "Aggregate income.")
For the various types of income, the means are based on households having those types of income. For household income and family income, the mean is based on the distribution of the total number of households and families including those with no income. The mean income for individuals is based on individuals 15 years old and over with income. Mean income is rounded to the nearest whole dollar.
Care should be exercised in using and interpreting mean income values for small subgroups of the population. Because the mean is influenced strongly by extreme values in the distribution, it is especially susceptible to the effects of sampling variability, misreporting, and processing errors. The median, which is not affected by extreme values, is, therefore, a better measure than the mean when the population base is small. The mean, nevertheless, is shown in some data products for most small subgroups because, when weighted according to the number of cases, the means can be computed for areas and groups other than those shown in Census Bureau tabulations. (For more information on means, see "Derived Measures.")
For the various types of income, the means are based on households having those types of income. For household income and family income, the mean is based on the distribution of the total number of households and families including those with no income. The mean income for individuals is based on individuals 15 years old and over with income. Mean income is rounded to the nearest whole dollar.
Care should be exercised in using and interpreting mean income values for small subgroups of the population. Because the mean is influenced strongly by extreme values in the distribution, it is especially susceptible to the effects of sampling variability, misreporting, and processing errors. The median, which is not affected by extreme values, is, therefore, a better measure than the mean when the population base is small. The mean, nevertheless, is shown in some data products for most small subgroups because, when weighted according to the number of cases, the means can be computed for areas and groups other than those shown in Census Bureau tabulations. (For more information on means, see "Derived Measures.")
Excerpt from:  Social Explorer; U.S. Census Bureau; American Community Survey 20072011 Summary File: Technical Documentation. 
The 20072011 ACS 5Year Summary File Technical Documentation > Appendix A. Supplemental Documentation > Subject Definitions > Population Variables > Income in the Past 12 Months > Income Quintile Upper Limits 