Timberlake and Williams (1984) offer a regression model to explain political oppression (PO) in terms of foreign investment (FI), energy development (EN), and civil liberties (CV). High values of PO correspond to authoritarian regimes that exclude most citizens from political participation. High values of CV indicate few civil liberties. Data were collected for 72 countries. The equation proposed by Timberlake and Williams is PO = a + bFI + cEN + d CV + random error,