One of the main challenges of survey research is declining response rates, which promts questions about the viability of traditional modes of data collection. The most recent DPES of 2017 combined three forms of data collection, a fresh samle interviewed face to face, a fresh sample interviewed online and an existing online panel (the 'LISS-panel '). Differences between the three turn out to be quite limited, so that we expect to be able to conduct future versions of the DPES by a multi-mode design.
All data are available to the research community. The data have been used mainly by political scientists communication scientists and sociologists for academic research. Yet, is has also been used by other stakeholders (e.g., the CBS and SCP). Its core focus is threefold:
1) describe and explain aggregate level changes in patterns of electoral behaviour.
As a result of the slow but steady accumulation of election study data over time, data allow us now to focus on longitudinal analyses of political behavior. The repetition of core survey questions in each subsequent election study is a necessary condition for testing theories of aggregate social, political and electoral change. Apart from many scientific journal and book publications, this dynamic perspective underlies several non-specialist books and journal contributions published in the past decade. These studies have resulted in a clear description and analysis of social and political change in which it is shown how old political and social ties weakened, while at the same time new dominant cleavages have not been firmly established yet.
2) explain changes in individual determinants of turnout and party choice.
Individual level models of voting behavior and political attitudes are well established in the academic literature. Originally, researchers strongly focused on the relationship between socio-economic background variables (social structure) and individual behavior. Partly because society changed and partly because theories of voting behavior were refined and became more sophisticated, the focus later shifted and diversified towards several types of issue voting. More recently, theories about the relative importance of candidates (indirect and direct effects of personality) and political parties (issues) are extensively discussed in the academic literature. Research questions about the media and campaign context have been studied intensively as well. The collaboration with the LISS-panel also enables us to study electoral change at the individual level, and link these changes to citizens' media exposure. Voters increasingly tend to postpone their decision how to vote until the very last days, and there is more electoral volatility than ever before. Campaign events may therefore have more impact on the election result than used to be the case.
3) explain the role of contextual determinants of the vote
To serve this third purpose, the DPES has been at the forefront of the Comparative Study of Electoral Systems (CSES). The CSES (Comparative Study of Electoral Systems) project, initiated in 1993, involves over 50 countries from all parts of the world. Its aim is threefold: it develops common survey modules to be included in the national election studies of each of the participating countries during a five year period; it collects standardized district level information about elections (candidates, parties, results); and it collects standardized country-level information about the elections and other macro-characteristics, which aims at harmonizing questionnaires across countries for comparative research.