Do opinion polls influence voters?

It's another election campaign — this time in Quebec — and another round of opinion poll bashing.

This past weekend, it was Quebec Liberal leader Jean Charest's turn.

Charest lashed-out at pollsters, claiming a Leger Marketing study that showed his party languishing in third place, was just wrong.

"The polls are not reliable. The polls are not reliable, and they've never been. How many times do we have to demonstrate it?" Charest said during a campaign stop, according to the Globe and Mail.

"We just had an election in Alberta where the day before the vote one party had a 10 point lead and the next day the other party wins by 10 points. Are you going to tell me that was the margin of error?"

The Alberta election not withstanding, Canadian pollsters have actually been very accurate over the past few elections.

Nevertheless, Charest's rantings raise an important question: Whether the polls are accurate or not, how much do they influence voters' intentions?

[ Related: Talk of sovereignty, promoting French culture is bad for Quebec's economy ]

It's a question that remains a contentious issue among academics.

On the one hand, when you ask voters if an opinion poll influenced their decision the answer invariably comes back as "no." In a 2007 U.K. study, for example, only 3 to 4 per cent of those surveyed said that opinion polls impacted their vote.

On the other hand, there have been several studies which claim to have documented an electoral effect.

A 2008 study by the University of Massachusetts -Amherst listed some of the prevailing theories:

1. Voter conformism' - ie: the bandwagon effect:

"The bandwagon effect occurs when the poll prompts voters to back the candidate shown to be winning in the poll, thus increasing his/her chances of being on the winner's side in the end."

2. Strategic Voting:

"These theories are based on the idea that voters will sometimes not choose the candidate they prefer the most, but another, less-preferred, candidate from strategic considerations."

3. Voter participation/abstention

"It is often suggested that supporters of the candidate shown to be significantly lagging behind may give up casting their ballots, resulting in a landslide victory of another candidate."

Such theories have been enough for some countries to introduce legislation banning opinion polls during election campaigns.

According to the Oireachtas Library & Research Service, opinion polls in Italy are banned for 15 days preceding an election, polls in Slovakia are banned fourteen days prior and in Luxembourg, polls cannot be published in the last 30 days before election day.

If Charest is hoping for an Luxembourg-style opinion poll ban in Quebec, however, he's probably out of luck.

In 1993, Parliament adopted legislation banning publication of opinion polls during the 72 hours before election day. This provision, however, was struck down by the Supreme Court of Canada, in 1998, because it violated the Charter's "freedom of expression" clause.

The new act prevents the publication of the results of new or previously unpublished opinion polls only on election day.

So, for now at least, Charest will have to stick to the tried and true line all politicians use: 'the only poll that matters is the one on election day.'

Quebecers go to that poll on September 4.

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