Legislative turnover and its sources: it’s the selection

The research note argues that legislative turnover can be decomposed into two main sources of newcomer entry into the legislature: entry by election and entry by selection. This is demonstrated using available data on political mandates in the lower chambers of Austria, Belgium, the Netherlands and the United Kingdom in the period 1945–2015. We observe that selection is the leading source of new member entry across country and across time. Most turnover happens prior to general elections. This appears to be a general rule characterizing the phenomenon. We speculate as to the reason why. The conditions under which election appears to overtake selection as a major source of new member entry are investigated.