Arlington County residents are the wealthiest in the state, according to the results of a study released last week by the Tayloe-Murphy Institute at the University of Virginia.

The per capita income for 1978 in Arlington was a whopping $14,675, compared with the statewide average of $7,721.

The same report erroneously indicated that Falls Church was head and shoulders above all other jurisdictions with a $19,533 personal income figure.

That number is inflated because incomes from Fairfax County were inadvertently figured in with the Falls Church figure. Even when the figures are adjusted, the income level for Fairfax County is not expected to change significantly.

The institute expects to release accurate information about Falls Church when the data becomes available.

Most other Northern Virginia jurisdictions also were well above the state average income: Alexandria -- $12,028; Fairfax City -- $11,586; Fairfax County -- $10,832; Loudoun -- $9,325 and Manassas City -- $9,762.

Only Manassas Park with $6,539 and Prince William with $7,513 fell below the state's average personal income level.

A spokesman for the Tayloe-Murphy Institute, which conducted the survey, said Northern Virginia's greater per capita income level was due to small family sizes in the region, combined with the region's nearness to the Washington metropolitan area and the accompanying high standard of living -- and high wages.

Greensville County in southern Virginia set the 1978 record for the lowest per capita income -- $4,296.

"When you get into the rural areas, the families are larger," explained John Kemp of Taylor-Murphy, "with that large population denominator, you get a lower per capita income."