Sampling error, however, is oversimplified when presented as a single number in reports that may include subgroups, poll-to-poll changes, lopsided margins and results measured on the difference.

Representative sampling and random sampling are two techniques used to help ensure data is free of bias. A representative sample is a group or set chosen from a larger statistical population ...

In the second clip, Caitriona Perry, former Washington Correspondent for RTE, Ireland’s public service broadcaster, talked about polling leading up to the 2016 election and the factors that ...