EUROPE is riddled with corruption—or so its citizens believe. Three-quarters of respondents to a Eurobarometer survey in 2013 said they felt that corruption was widespread in their country; in Italy the figure was a cynical 97%. Corruption, as measured by such surveys, seems to sap growth. A report published in March by RAND Europe, a think-tank, claimed it costs the continent €179 billion-€990 billion ($203 billion-$1,130 billion) a year.

But getting accurate data on corruption is inherently difficult. Perception-based measures are often used, but economists have long questioned whether these reflect reality or common biases. Just as people systematically overestimate levels of immigration, what if they report corruption according to what they feel, rather than what they know?

A working paper by Lucia Rizzica and Marco Tonello of the Bank of Italy offers evidence about one potential source of bias in Italy: the media. News reports provide information about instances of corruption, but they also communicate widely held views about its prevalence.

The authors test whether people’s perceptions of corruption are influenced by the news. People are asked about the chances of a public servant suggesting a bribe, or a corrupt public servant being jailed. Over the same time that people were surveyed, the economists constructed a measure of exposure to corruption-related news, by counting the number of times corruption-related buzzwords appeared on the front pages of 30 national and local online newspapers.

People do seem to respond to media coverage by becoming more pessimistic about corruption in public institutions. An increase in potential news exposure of one extra story raises perceptions of corruption by around 3.5% and cuts trust in the effectiveness of the judiciary system by around 5.2%. This is not necessarily evidence of misinformation. Journalists are meant to hold those with power to account for their misdeeds; the results could suggest that the public is updating its views given new information.

But the researchers split the news coverage into two types: reports of specific instances of corruption, such as a new bribery investigation into a named politician, and more general claims, such as a discussion of whether Italy is more corrupt than other countries in Europe. When the researchers exclude days when only fuzzier claims are reported, the statistically significant relationship between news and perceptions of corruption disappears. In contrast, when the researchers excluded days when specific instances of corruption were discussed, the relationship between the news and public gloom strengthened. In other words, Italians’ view of corruption appears to be shaped more by waffle than by hard news.

Although only suggestive, the study is cause for concern. The media can set the agenda, but also distort it. There is some countervailing evidence, that relative rankings of corruption do have some validity: diplomats from countries where corruption is seen as more pervasive are less likely to pay parking fines, for example. But if perceptions are heavily influenced by the media buzz, then levels of corruption might be exaggerated. In other words, measures of corruption could themselves be corrupted.