Correlated columns

Two columns are correlated if the value of one column is related to the value of the other column. For example, state name and country name columns are strongly correlated because the city name usually, but perhaps not always, identifies the state name. The city of Conshohoken is uniquely associated with Pennsylvania, whereas the city of Boston exists in Georgia, Indiana, Kentucky, New York, Virginia, and Massachusetts. In this case, city name is strongly correlated with state name.