DEMO: Spain: pollsters and the uncertainty range

DEMO article. Replace it with real content.

Some agencies consistently give a party more or less than the others. This is called a “house effect” and you can see it in the Pollsters table on the Spain page.

A positive number means the agency gives that party more, on average, than the local trend of the other polls. For agencies with few polls the deviation is shrunk towards zero.

Sample size matters too: a poll of 2,000 respondents is more reliable than one of 600, so it carries more weight in the average.

The uncertainty range in the chart is not a formal confidence interval. Far from an election the real result can deviate even more.

To download the data, use the CSV and JSON buttons below the chart.