Are French pollsters cheating? The jury is still out

By D.R.

THE first rule of polling analysis is to take outlier results with a liberal helping of salt. Whenever a large number of surveys are conducted using proper random sampling techniques, a handful are all but guaranteed to yield results far from the consensus: of every 20 polls with a margin of error of three percentage points, you’d expect one to miss by six or more. Rather than suffering whiplash any time an atypical poll is published, seasoned election forecasters recommend focusing on the slower-moving averages.

Rarely has such sage counsel proven less relevant than in the 2017 French presidential campaign, where outlier polls have been closer to extinct than endangered. Of the 11 surveys taken in the past five days, every single one had Marine Le Pen between 21.5% and 23% of the vote, Emmanuel Macron between 22% and 24%, François Fillon between 18% and 21%, Jean-Luc Mélenchon between 18% and 22% and Benoît Hamon with either 7.5% or 8%. Such metronomic consistency has been the rule, not the exception: just look how closely the dots (each an individual survey) cluster around the trend lines in our poll tracker below. During the past two months, the average poll result for a single candidate has differed from the average of all other surveys taken in the surrounding time period for that candidate by a paltry 0.7 percentage points.