The Impact of Online Platforms on Public Opinion

The Impact of Online Platforms on Public Opinion

The Impact of Online Platforms on Public Opinion

Regarding the European Union

Laura Sudulich, ULB

Leonardo Baccini, LSE


An information environment is vital to the capacity ofcitizens to learn about politics, their ability to link political preferences to parties and policies and to assess the performances of institutions and political actors. In most instances, people gather politically relevant information via the mass media rather than through direct interaction with political elites. The role of the mass media is therefore key to the correct functioning of society (Castells 2000; Delli Carpini and Keeter 1996). There is no shortage of evidence showing that the mass media exert a crucial influence on public opinion formation (Zaller (1992); for a review of major contributions, see Bennett and Iyengar (2008)).

The mass media are particularly important when considered in relation to the formation of opinions, the forming of political awareness and voting behaviour in the context of the European Union, since citizens typically do not experience any direct contact with European institutions. Thus, citizens necessarily rely on the mass media when (in)forming their opinions about the European Union (hereafter EU). Additionally, a widespread ignorance of EU politics and policies among members of the European public is notorious and persistent. Over a third of Europeans are unable to name any EU institution; the percentage of citizens claiming to know little or nothing at all about ‘the people who run the various EU institutions and the leaders of the EU’ is a striking 73%. A similarly high number of subjects (74%) report knowing little or nothing at all about ‘The allocation of roles played by the various institutions (who does what?)’ (Eurobarometer 77.4). The impact of radio, television and newspapers has been extensively debated in relation to electoral behaviour and attitude formation towards the EU (De Vreese 2003; De Vreese and Boomgaarden 2006; Schuck and De Vreese 2006), while the influence of the Internet_ is currently under-explored.[1] This is in spite of a significant average penetration rate of 75.5% across member states, with several countries – The Netherlands, Sweden, Denmark – registering over 90% coverage (World Bank 2013).[2] Moreover, a real word trend indicates that the Internet is rapidly becoming a fundamental source of information about European matters. Between November 2011 and December 2012, the percentage of citizens reporting that they had gathered information on the European Parliament on the World Wide Web went up by 10%, from 33% to 43% (Eurobarometer 78.2).

This paper takes a first step to addressing whether consuming online information about the EU is responsible for variation in public opinion regarding it and whether this process bypasses or encompasses political knowledge. Specifically, we explore how different type of sources affect public opinion. In so doing, we bridge studies of public opinion and media effects to contributions addressing online source credibility (for a review see Metzger 2007). The latter are mostly based on experimental evidence and do not directly address political learning or opinions, while the former tends to rely on observational data and often disregards the nuances of digital environments.

We use data from Eurobarometer 76.3 (November 2011) posing a large battery of questions on media use for political information consumption based on arepresentative Europe-wide sample of individuals. Importantly, this survey contains a unique array of items on online political news consumptionhabits. In addition, we provide anin-depth analysis of the effects of a particular type of platform - the Irish Referendum Commission website - on electoral behaviour in the context of the Fiscal Compact Referendum held in the Republic of Ireland on May 31st 2012.[3]Making use of an original survey, we test the micro-foundations of our argument by isolating the effects of online information gathered specifically with regard to a single policy i.e. the Fiscal Compact. Specifically, we explore the impact of online newsgathering on the knowledge of such a policy, and on actual voting behaviour.

We find that consuming information online has an effect on the opinions of those who consult the websites of traditional media and institutions; this is mediated by an increase in political knowledge. Websites thatare by default a mixture of vetted information and non-fact-checked information prove unable to do this. In fact, Those who gather their information about the EU mostly viablogs, social networking sites or video sharing platforms experience no significant effects on opinions andneither they appear to gather knowledge. For those who actually experience an effect by visiting institutional websites or digital versions of news media an increase in knowledge turn into positive views about the EU. Along similar lines, the analysis on the Irish Fiscal Compact Referendum confirms that visiting an institutional website - namely the Referendum Commission’s site – increases self-perceived knowledge of the specific policy at stake and the likelihood of voting in favour of the Fiscal Compact Treaty. In the mare magnum of data available on the web, credible fact-checked sources stand out in providing viable knowledge that serves to orient citizens’ opinions.

The article proceeds as follows: in the next section we outline the relationship between online-based information, political knowledge and public opinion on which we base our working hypotheses. We then discuss our main empirical strategy hinging on causal mediation analysis and describe the data. In the following section, we outline and discuss the results of our analysis.We then run a further test to account for the endogeneity intrinsically associated with the relationship between media usage and public opinion. Next, we explore the micro-foundations of our argument analysing the Irish Fiscal Compact Referendum survey. We conclude by examining the implications of our findings.

Information, knowledge and the World Wide Web

Information is the data that allow individuals to acquire (politically) relevant knowledge and to form or redefine their beliefs. It can be gathered from direct experience –attending a candidate debate, correspondence with an MP – or by being exposed to reports. These reports can be based on the experience of people in one’s social network – e.g. a friend telling of his/her experience in dealing with local government – or can be provided by mass media. Acquiring information through direct experience of EU institutions and policies can be substantially ruled out. The same applies to information obtained via personal networks as ‘very few citizens have first- or even second-hand contact with Community affairs in Brussels’ (Dalton and Duval 1986, 186).

Political knowledge is the state of awareness of facts that matter to orient people’s opinions and choices. The acquisition of knowledge depends upon the availability of information, and so does the redefinition of what Bartels (1993) calls the ‘fund of knowledge’. Newly acquired information allows individuals to update their pre-existing knowledge – for those who had some – and provides new knowledge to those who had none before. The mass media are therefore key to educating the public by making the information available and accessible (Holtz-Bacha and Norris 2001). Information acquired via the mass media can then translate into in-depth knowledge, superficial acquaintance, or even no knowledge as a result of it being, unclear, noisy or redundant.

A substantial corpus of studies has unveiled differences among traditional media in their capacity to translate information into knowledge that subsequently affects political evaluations (for a review, see (Norris and Sanders 2003)). While several studies support the idea of the superiority ofprint (Robinson and Davis 1990; Robinson et al. 1986), others cast doubts on it (Graber 2001; Mondak 1995), with no ultimate consensus on which medium carries the highest learning potential for the public. Despite the different conclusions reached by these studies, the literature on traditional media relies on a widely shared – if implicit – assumption: the information provided is both factual and relevant. Media publishers and regulatory authorities act as gatekeepersto what can be broadcast or printed, and media editors, through the process of indexing (Bennett 1990), select what is relevant for the public to know(Flanagin and Metzger, 2000). The multiplicity and segmentation of information producers on the World Wide Web (Bimber 2003) cast some doubt on the applicability of this assumption to the Internet. One of McLuhan’s (1964) insights in formulating the well-known the medium is the message theory was that “the content of any medium is always another medium”.

The Internet essentially contains all the other mass media that preceded it: the printed press, TV, and radio. All major news outlets nowhave an online version. Additionally, there are many other online spaces that deliver politically relevant information: the official websites ofinstitutions, social media sites – including social networking sites like Facebook and Twitter as well as sharing platforms like wikis and YouTube – and blogs. Online information can therefore take the most diverse shapes, depending on the source and hosting platform: from credible news producers to unverifiable information posted by individuals simply voicing their own opinions. In the words of Patterson, “the internet is at once a gold mine of solid content and a hellhole of misinformation” (2013: 79). These structural differences with respect to traditional media are likely to affect the opinions and behaviours of those who have integrated online news consumption into their media usage habits. The nature of online-based information may also affect the process through which individuals translate information into political knowledge.

Lupia and McCubbins(1999, 25) point out a key element of the relationship between information and knowledge: ‘although you cannot have knowledge without having information, you can have information without having knowledge’. Information that does not provide knowledge is either redundant or issimply noise. While absorbing redundant information is a possibility when gathering information via any media, the Internet maximizes the potential for the amplification of noise by creating an environment where noise and signal are often indistinguishable (Ayres 1999).

Online spaces vary dramatically in the heterogeneity of their content and in the extent to which they host unverified versus verified facts. For instance, the website of a major newspaper is likely to publish content that is verified and has been provided by accredited sources. At the other end of the spectrum, platforms like blogs and forums are, by definition, aggregators of comments and opinions, often seeking to advocate more than to report (Scott 2007). Experimental research has shown that websitescredibility is best understood as a perceptual attribute, but working with survey data rules out respondents’ self-assessment (for a review of online perceived credibility research see: Flanagin and Matzger 2007). Therefore, we opt for a classification of sources that both builds on what shown by these studies and accounts for the fact that platforms that host information created by a more heterogeneous set of producers and of mixed nature are more likely to carry greater amounts of noise. In Table 1 below we classify hosting platforms in terms of the type of information they provide and the information producers.

[Table 1 about here]

We thusempirically analyseseparately the effects of platforms that have a strong potential for the amplification of noise from those that are most likely to maximize fact-checked information, in order to gather a more finely-grained understanding of how the new media affect individuals’ opinions. Formally, we test whether the following hypotheses hold true:

H1: Online platforms providing vetted information increase knowledge of the EU and significantly impact upon citizens’ opinions about it.


H2: Online platforms providing miscellaneous information do not increase knowledge of the EU and fail exercising an impact upon citizens’ opinions about it.

Given the large amount of variation across platforms, we expect the mechanism to work through the knowledge channel only for those platforms that are more likely to facilitate users in distinguishing the news from the noise. Knowledge is a well-established predictor of attitudes; therefore increases in knowledge should filter the effects of information acquisition, particularly so in the wake of what we know about widespread ignorance of European citizens on EU level matters and institutions. Media effects are more consequential where previous opinions are weak, and the second order theory (Reif and Schmitt 1980) clearly indicates that attitudes towards the EU are weaker than attitudes towards national government, making media effects particularly well placed to impact upon citizens’ opinions.

Empirical strategy

To test our hypotheses we perform three empirical analyses. First, as a result of our theoretical framework, we implement a causal mediation analysis model. This allows us to distinguish the direct effect of online information consumption from its mediated effect through increases in knowledge of EU matters. Causal mediation analysis is the core test of our argument. Second, we implement instrumental variables to mitigate concerns on reverse causality. We note that while instrumental variables are a useful tool to address the endogeneity problem, they are substantively different from causal median analysis. In particular, instrumental variables do not allow us to disentangle the mediated effect of online information for its direct effect on attitudes toward the EU. Third, we validate the results of our cross-country estimates with original micro-level data on the Irish Fiscal Compact Referendum.

Let’s start describing the research design of the causal median analysis. Causal mediation analysis allows exploration of the role of an intermediate variable that lies along the causal paths between the treatment and the dependent variable (Hicks and Tingley 2011; Imai, Keele, and Yamamoto 2010). In our case, knowledge about the EU is the mediator that lies along the causal path between information gathered online and attitudes towards the EU. The path mode is illustrated in Figure 1.[4]

[Figure 1 about here]

To carry out the causal mediation analysis, we rely on the STATA 13 ‘mediation’ package developed by Hicks and Tingley (2011). The model for both the mediator variable and the outcome variable is an ordinary least squares (OLS) regression. We include country fixed effects to account for cross-country heterogeneity and mitigate omitted variable problems. We use robust standard errors and we run 1000 simulations for the quasi-Bayesian approximation of parameter uncertainty.We are unable to run an ordered logit (or probit) – which would be more appropriate given the outcome variables – as this is not supported by the ‘mediation’ package. However, we run simple ordered probit models – reported in the online appendix (Table A5) -the results of which are very similar to those from the OLS regressions. This makes us confident of the reliability of the estimations when we implement the causal mediation analysis.


We use data from Eurobarometer 76.3, which contains a large battery of items on media use for political information on EU matters. We exclude observations from countries that were not members of the EU at the time of the data collection (November 2011).

Outcome variable

The outcome variable captures respondents’ attitudes towards the EU. The question on which we build our dependent variable was posed as follows:

“In general, does the EU conjure up for you a very positive, fairly positive, neutral, fairly negative or very negative image?”[5]

The resulting variable ranges from 0 to 4 where 0 indicates ‘very negative’ and 4 ‘very positive’.

Treatment variables

We firstly set apart those who gathered most of their information on political matters about the EU on the word wide web.[6]

To capture different types of information sources online we rely on the following dummy variables:

  • A variable that scores 1 if respondentsexclusively use ‘institutional and official websites (government websites, etc.)’ to gather information on European matters, and 0 otherwise;
  • A variable that scores 1 if respondents exclusivelyuse ‘information websites (websites from newspapers, news magazines, etc.)’ to gather information on European matters, and 0 otherwise. We label this variable traditional media websites;
  • A variable that scores 1 if respondentsexclusively use ‘online social networks’ to gather information on European matters, and 0 otherwise;
  • A variable that scores 1 if respondentsexclusively use ‘blogs’ to gather information on European matters, and 0 otherwise;
  • A variable that scores 1 if respondents exclusivelyuse ‘video hosting websites’ to gather information on European matters, and 0 otherwise.

These variables are generated on the basis of responses to the following question:

On the Internet, which of the following websites do you use to get news on European political matters?“ (a) Institutional and official websites (governmental websites, etc.)(b)Information websites (websites from newspapers, news magazines, etc.)(c)Online Social Networks (d)Blogs(e)Video hosting websites(f)Other.

Figure 2 shows the distribution of the country averages of our five treatments. The take-home message from this figure is that at the time of the fieldwork the websites of traditional media outlets were, by far, the most visited platforms in every country. The second most preferred platforms for gathering information on EU matters were institutional and official websites, while the use of blogs, online social networks and video hosting websites was very limited across the entire sample. As one may reasonably expect the percentage of those who gather most of their information about the EU on Online Social Networks and Blogsis quite small (below 5% for both types) and minuscule with regard to Video hosting websites.

[Figure 2 about here]

Given this structural characteristic of the data, we aggregate the five dummies in two treatments. On the one hand, we create a variable that scores 1 if respondents exclusivelyuse ‘institutional and official websites’ or ‘traditional media websites’. We label thisfact-checked websites. On the other hand, we create a variable that scores 1 if respondents exclusivelyuse ‘online social networks’or ‘blogs’ or ‘video hosting websites’. We label thismiscellaneous websites. By implementing this additional measure we minimize concerns about the results being driven by few observations.


For the mediating variable we use an index of objective political knowledge about the EU compiled by the Eurobarometer team and available in the dataset. It ranges from 0 to 2 (bad, average, good) and it is based on the answer to the following standard question: