Ghana elects on national level a head of state, the president, and a legislature. The president is elected for a four-year term by the people. The Parliament of Ghana has 275 members, elected for a four-year term in single-seat constituencies. The presidential election is won by having more than 50% of valid votes cast, whilst the parliamentary elections is won by simple majority, and, as is predicted by Duverger's law, the voting system has encouraged Ghanaian politics into a two-party system, creating extreme difficulty for anybody attempting to achieve electoral success under any banner other than those of the two dominant parties. Elections have been held every four years since 1992. Presidential and parliamentary elections are held alongside each other, generally on 7 December every four years. Scholars review of elections Presidential Parliamentary See also Electoral calendar Electoral system Electoral Commission of Ghana List of general elections in Ghana Ethnic voting in Ghana Ethnic voting is the idea that people utilize candidates' ethnic identity to decide who can be best trusted to follow through with their promises for goods to their coethnic constituents as payment for their vote. This form of vote buying in which one's vote is paid for through a targeted public good is known as clientelism and is especially popular in sub-Saharan African countries. Kanchan Chandra, one of the leading academics in Ethnic Politics, claims that there are several causes for this phenomenon in Africa. First, the individual has an incentive to seek out public goods for their vote because of one's perception that their vote individually will not lead to altering the election. Through this logic, Chandra displays that there is an incentive for people to organize for casting their vote within this context because, even if the one does not benefit from this vote individually, their collective vote may allow this group some access to favoritism from the candidate if they win thus establishing greater value in their collective votes. Furthermore, the candidate has an incentive to provide benefits to groups for their vote because an individual method of distributing jobs and services may create conflict in which providing a good to one voter may deprive another voter of that same good; therefore, a group method of distribution both allows for less conflict and greater insurance for the voter that the candidate will follow through on their end. To gain access to a salient group