“…Sometimes, researchers tend to use the relative price of imports, ratio of import price to domestic price, when multicollinearity exists (Doroodian, Koshal, and Al-Muhanna, 1994;Abbott and Seddighi, 1996;Sanos and Montanes, 2002;Agbola and Damoense, 2005). However, other researchers have used import and domestic prices as separate variables in estimating import demand functions (Fuller, Gutierrez, and Capps 1992;Fuller, Bello, and Capps, 1992;King, 1993;Peridy, Guillotreau, and Bernard, 2000;Fischer, 2004). Gross Domestic Product (GDP) is generally used as a measure of income, however, many researchers have pointed out that consumption expenditure might represent a better proxy of income than GDP (King, 1993;Periday, Guillotreau, and Bernard, 2000).…”