Abstract: Election behaviour is the result of many influences. The decision to vote for a particular party depends on various factors, ranging from the voter’s social status and income to the structure of political options and the impact of the election campaign. These factors may include the electoral system as well. Especially when the voters are familiar with the operation of the electoral system, they can adjust their choice to the assumed effect. This paper examines the relation between the effect of the electoral system on the representation of the parties and candidates and the electoral behaviour of the voters in elections to the House of Deputies of the Parliament of the Czech Republic, especially in the latest elections in 2006. The system of proportional representation used in the Czech Republic leads to disproportional representation of the parties. Voters have known one of the causes – legal threshold – for a long time. The other cause – the natural threshold – is a recent phenomenon. Differences in knowledge result in the fact that when the voters make a decision, they think about it, while in the other case they probably often do not even suspect its existence. Another element to which the voters have become already accustomed and which is in increasing use is the possibility to give preferential votes, which can alter the order of the candidates in the party list. With the assistance of dates from election statistics and data from the survey: Czech Election Study 2006, the author analyzes the consequences of the three components of the electoral system: legal threshold, natural threshold, and preferential personal voting.

Keywords: Electoral system, Voting behaviour, Electoral threshold, Czech Republic, Proportional representation