Notes:

Bolded: ACS 90% MOE crosses 0 (no data still with MOE)
Arlington County data is weighted by the number of units within the property
- Not all properties have a units counts, which drives the number of housing units down (especially when the NA is for a multifamily)
- Number of unknown units count: 206 (2009), 233 (2010), 237 (2011), 248 (2012) and 463 (2013)
All prepared Arlington County data are used in the tabulations. When calculating census tract and block group (bg) comparisons, only those data that are within a designated tract/bg are included. When geocoding addresses along the county boarder, rooftop coordinates can occur outside the county. When merging tract to coordinates, these properties would not receive a tract/BG ID number

County

5 Year

Geography:	Arlington County, Virginia
Dataset: 2009-2013 5-year	Table B25035. MEDIAN YEAR STRUCTURE BUILT [Universe: Housing Units]
Description of Variable	ACS Benchmark		Direct Estimate Arlington Country Real Estate
	Estimate	90%MOE	SE	Estimate	Difference	Within 90%MOE?
Median year structure built	1968	2	1	1961	7	NO

Geography:	Arlington County, Virginia
Dataset: 2009 1-year	Table B25035. MEDIAN YEAR STRUCTURE BUILT [Universe: Housing Units]
Description of Variable	ACS Benchmark		Direct Estimate Arlington Country Real Estate
	Estimate	90%MOE	SE	Estimate	Difference	Within 90%MOE?
Median year structure built	1965	2	1	1960	5	NO

Geography:	Arlington County, Virginia
Dataset: 2010 1-year	Table B25035. MEDIAN YEAR STRUCTURE BUILT [Universe: Housing Units]
Description of Variable	ACS Benchmark		Direct Estimate Arlington Country Real Estate
	Estimate	90%MOE	SE	Estimate	Difference	Within 90%MOE?
Median year structure built	1967	2	1	1961	6	NO

Geography:	Arlington County, Virginia
Dataset: 2011 1-year	Table B25035. MEDIAN YEAR STRUCTURE BUILT [Universe: Housing Units]
Description of Variable	ACS Benchmark		Direct Estimate Arlington Country Real Estate
	Estimate	90%MOE	SE	Estimate	Difference	Within 90%MOE?
Median year structure built	1970	3	2	1961	9	NO

Geography:	Arlington County, Virginia
Dataset: 2012 1-year	Table B25035. MEDIAN YEAR STRUCTURE BUILT [Universe: Housing Units]
Description of Variable	ACS Benchmark		Direct Estimate Arlington Country Real Estate
	Estimate	90%MOE	SE	Estimate	Difference	Within 90%MOE?
Median year structure built	1969	3	2	1961	8	NO

Geography:	Arlington County, Virginia
Dataset: 2013 1-year	Table B25035. MEDIAN YEAR STRUCTURE BUILT [Universe: Housing Units]
Description of Variable	ACS Benchmark		Direct Estimate Arlington Country Real Estate
	Estimate	90%MOE	SE	Estimate	Difference	Within 90%MOE?
Median year structure built	1973	2	1	1961	12	NO