Discipline: Psychology, Social Science
The study explains the proportionality of Party List election results in 1998, 2001, 2004, and 2007 using Counter Duvergerian Psychological Effect framed in the context of Historical Institutionalism. According to the claim of the theory, as the length of establishment of electoral system increases, the factors on proportionality in terms of the number of political parties competing, vote fragmentation, and deviation from proportionality decrease. The result of the study finds no significant relationship between the length of establishment and factors on proportionality.