Italians and Americans score worst when it comes to correctly assessing basic facts of modern life, such as what proportion of the population are immigrants or what percentage of teenage girls get pregnant.
Swedes and Germans do best, although even they consistently get things wrong, according to a survey of 14 industrialized countries released on Wednesday.
The analysis by market research organization Ipsos MORI shows how far perceptions stray from reality across a range of issues as people struggle to get a precise handle on aspects of society that are seen as risks or worries.