In CBC's poll tracker, why do the probabilities of winning not add up to 100%?


In CBC's poll tracker at:, probabilities of winning the 2019 Canadian federal election are provided.

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Currently, these are 11% Liberal majority, 39% Liberal minority, 42% Conservative minority, and 6% Conservative majority. By my count, these probabilities add up to 98%. Shouldn't this be 100%?

Jimmy Vailer

Posted 2019-10-15T17:59:10.730

Reputation: 135



I don't see any explanation on their Full Methodology Info page, but when percentages don't add up to 100%, the usual answer is that it's due to rounding, so 11% might actually be 11.4%, which was rounded down to 11. Among 4 options, rounding could explain almost all of the missing 2%.

Another possibility, is that these 4 options don't represent all possibilities. For example, it's possible that the Liberals and Conservatives get equal numbers of seats, but neither has a majority (due to seats gained by other parties)


Posted 2019-10-15T17:59:10.730

Reputation: 19 513

Indeed, I can see the extra 1-2% being a tie. – Joe C – 2019-10-15T18:10:10.197

I thought of a third party (such as the NDP) winning as a possibility for making up the 1-2%, but that seems to be ruled out by the fact that their maximum projected seats is only 60. The possibility of a rounding down or a tie makes sense though. Thanks. – Jimmy Vailer – 2019-10-15T19:09:07.330