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Liberal Leader Justin Trudeau, shown June 12, 2013.
Liberal Leader Justin Trudeau, shown June 12, 2013.
(SEAN KILPATRICK/THE CANADIAN PRESS)

Are Trudeau’s Liberals really up by 10 points? How to know when to trust a poll

News stories about polls never get as much attention as when the survey results are unusual. Compared to a stable trendline, a big gain, a steep loss, or a wide lead is far more interesting, regardless of whether or not the result is accurate. In most cases, in fact, that extra attention is being given to what is known as an outlier. But can we identify an outlier when we see one?