About the Towns Economics Data
There are 14 incorporated towns in Northern Virginia. For comparative purposes, Northern Virginia counties and cities, Commonwealth of Virginia, and United States data are provided in the graphs.
About the Data and Proper Data Interpretation
The economic data of incorporated towns is sourced from the 2000 Census and the American Community Survey (ACS). All of the incorporated towns in Northern Virginia have a population of less than 65,000 persons. One-year ACS estimates do not exist for incorporated places with a population of less than 65,000. All incorporated towns and places in the United States are included in the five-year ACS estimates.
It is important to note that any data sourced from the ACS is based on a small sample of the population of a place. The ACS estimates for places with smaller populations such as Clifton, Dumfries, Hamilton, Haymarket, Hillsboro, Lovettsville, Middleburg, and Quantico can be unreliable if the margin of error is large. A town's margin of area for an ACS data piece can be found by hovering over the town's data in a graph. If there is a large increase or decrease in the estimate from one time period to the next, and the margin of error is large and overlaps other periods, then the large change between time periods is likely due to statistical sampling error and is not considered statistically significant. In addition to the margin of error, the accuracy of the American Community Survey data for an area can be gaged by evaluating the trend. If the data has a clear trend then the data from one period to the next can be deemed reliable.
Only data variables that are deemed relatively reliable have data provided at the town level. For instance, poverty data is unreliable for many towns in Northern Virginia so that data is not being provided.