FIRST READING: Why the massive Liberal poll leads might be an illusion

Detail from a Wikimedia Commons chart tracking opinion polling since the 2025 federal election. Photo by Wikimedia Commons

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TOP STORY

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As the Liberals enjoy some of the most explosive polling leads in Canadian history, a leading pollster is suggesting that it’s mostly a product of mathematical error.

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This week, Abacus Data CEO David Coletto suggested that many of his peers are chronically undercounting Conservative voters, presenting a “distorted version” of the electorate to the public.

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“I do not believe that other pollsters are purposively doing anything wrong,” he wrote in an online post. He then suggested that Canadian surveys were routinely showing “a larger Liberal advantage than may actually exist in the electorate.”

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Abacus Data’s own surveys have indeed been showing a Liberal lead for the last few months, but not at the same margins as other polls.

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One of their most recent surveys, published on March 24, showed the Liberals with a seven-point lead over the Conservatives (44 per cent Liberal to 37 per cent Conservative).

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This is way out of step with other Canadian pollsters, all of whom are reporting a Liberal lead of at least 10 points.

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An Ipsos poll on April 7 tracked a lead of 12 points (45 per cent Liberal, 33 per cent Conservative). A Leger poll on March 30 recorded a lead of 14 points (48 per cent to 34 per cent).

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And a particularly dramatic mid-March poll by Ekos recorded a lead of more than 20 points; 47.5 per cent Liberal to 27 per cent Conservative. This particular survey represents one of the largest Liberal poll leads ever recorded in the history of Canadian opinion polling.

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“I don’t believe the Liberals are leading by double digits,” wrote Coletto in an April 11 social media post. He added that the disparity was arising due to “under representation of conservative voters.”

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In a follow-up analysis published on the official Abacus Data website, Coletto suggested that the problem lay in how surveys were being weighted.

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Even a poll with a sample size of a few thousand people isn’t going to be an accurate reflection of the Canadian electorate. The way pollsters traditionally get around this is by tweaking the results based on demographics such as region or age.

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As an example, Manitobans represent about four per cent of the Canadian population. So if a pollster has a sample that’s only two per cent Manitobans, they might decide to give those responses extra weight in order to more accurately reflect Manitoba’s share of overall Canadian public opinion.

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Coletto’s claim is that demographic weighting, on its own, is consistently misrepresenting the share of the Conservative vote, and blowing out the Liberal lead.

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The blog post was motivated in part because Abacus Data keeps delivering numbers that are way more favourable to the Conservatives than any other pollster.

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As recently as January, Abacus Data had the Conservatives and Liberals tied at 40 per cent, when everybody else was tracking a Liberal lead of between three and five points.