A: In a scientific experiment, a confounding variable is a secondary, changing condition that muddies the experimenter's hypothesized inference between cause and effect. Researchers must be meticulous about experiment design to control for confounding variables and to protect the integrity of their findings.
Fairfax County, officially the County of Fairfax, is a county in the Commonwealth of Virginia. As of the 2010 census, the population was 1,081,726, in 2014, the population was estimated to be 1,118,883, making it the most populous jurisdiction in the Commonwealth of Virginia, with 13.6% of Virginia's population.lexandria County was returned to Virginia in 1846, reduced in size by the secession of the independent city of Alexandria in 1870, and renamed Arlington County in 1920. The Fairfax County town of Falls Church became an independent city in 1948.
According to the U.S. Census Bureau, the county has a total area of 406 square miles (1,050 km2), of which 391 square miles (1,010 km2) is land and 15 square miles (39 km2) (3.8%) is water. Fairfax County is bounded on the north and southeast by the Potomac River.