Voting in the European Parliament
As mentioned above, there are essentially three different forms of voting in the EP. Most of the time, members vote by a simple show of hands, as this is the quickest way and there are frequently more than a hundred individual votes on legislative and non-legislative texts, amendments, and resolutions to be taken during a plenary session (cf. Corbett et al. 2011, 200). When MEPs vote by show of hands, the session president is responsible for judging where the majority lies. If the president is unsure or the president’s judgment is challenged by any MEP, an electronic check is carried out. For this, MEPs use the electronic voting machines installed on their tables. They insert their voting card and press the respective button to cast a yes- vote, a no-vote, or an abstention. The exact vote count is then displayed on screens in the plenary. The electronic voting system is also used for the third type of voting: RCVs. In contrast to electronic votes, where only the overall result of the vote is made public, in RCVs, the voting behavior of each individual MEP is recorded and later published in the minutes.
Quantitative research on the EP relies on the results of these RCVs to a large extent. However, not all of the votes in the EP are taken by roll call. Furthermore, RCVs do not occur randomly, but are requested by groups of MEPs. Existing research shows that this has the effect that votes on some issues are more likely to become roll calls than votes on other issues. This raises speculations about a potential bias in RCVs.
The original data on voting in the EP was put together by a research team comprising Simon Hix, Abdul Noury, and Gerard Roland. They collected data on all recorded votes from 1979 onwards. Their dataset contains information on whether an MEP voted “Yes”, “No”, or abstained (or whether the MEP was present but did not vote, was absent, or not an MEP at the time of the vote). The raw data is available online.6 Based on these data, numerous studies have analyzed the voting behavior of MEPs, the most exhaustive of these studies being Hix et al. (2007).
However, one has to be aware that recorded votes (RCVs) are only a fraction of all votes in the EP. Until 2009, RCVs were only taken if at least 40 MEPs requested this in advance. In practice, it was mostly one or more of the EPGs that demanded the vote to be held by roll call. This gave rise to the suspicion that RCVs are not called randomly, but rather strategically by the groups, for example, to display a certain position or even to put pressure on group members to vote according to the group line. If these suspicions are true, there might be a selection bias, meaning that RCVs differ in their characteristics from the full population of votes. As RCVs might not be representative for all votes, the findings based on RCVs might also not be representative.