EU Commission defends Eurobarometer methodology

But the response rates have decreased, and are so low in some member states that using the data presents problems and is likely to result in a systematic overestimation of public support for the EU, according to experts cited by the Danish newspaper Dagbladet Information earlier this week.

In the most recent Eurobarometer survey for which response rates have been calculated, and obtained by the Danish newspaper, the rate was 14 percent in Finland, 15 percent in Germany, 22 percent in Italy, 27 percent in the UK, 31 percent in Greece and France, 34 percent in Spain, and 40 percent in Portugal.

The low response rate might cause distortions in measuring euroscepticism, according to Dagbladet Information, because citizens who are most critical of the EU tend to be less inclined to participate in an interview about the bloc.

The commission said respondents are not told in the beginning of their face-to-face interview that the survey is done for an EU institution in order to avoid such bias.

"The Eurobarometer survey is a reliable instrument to measure the state of public opinion in the EU over time," commission spokeswoman Dana Spinant said.

"There is no evidence that people that are most likely to complete Eurobarometer surveys are actually the ones that are more positive to the EU, we have not seen such evidence," she added.

The standard Eurobarometer is conducted twice a year on public opinion trends in member states and the EU, with each survey consisting of around a 1,000 face-to-face interviews per country.

Other, more specific and faster surveys, the flash Eurobarometers, are done through "ad hoc thematic telephone interviews", according to Eurobarometer.

"Eurobarometer is not a tool to collect statistics, it rather provides a snapshot of public opinion perceptions at a give time," Spinant added.

The latest Eurobarometer, published in August, found that after the European elections in May, positive associations with the EU in the European public opinion, such as freedom to travel and work anywhere, peace and economic prosperity, had increased.

It also found that a large majority of Europeans are convinced that it is better to be in the EU than outside, with 59 percent saying they disagree that their country "could better face the future outside the EU".

Trust in all EU institutions has also increased since autumn 2018, the survey found.

Some 51 percent of the respondents trust the European parliament (while 36 percent "tend not to trust"), in the EU commission 46 percent have trust, 42 percent in the European Central Bank, 40 percent in the European Council and 37 percent in the council of the EU, consisting of member states.

The August survey also said that 45 percent of Europeans (a two percentage points increase since autumn 2018) have a positive image of the EU, while 17 percent (three percentage points less) have a negative image of it and 37 percent (one percentage point increase) have a neutral image.