What do Canadians think about the country's mission against ISIS in the Middle East? Finding out the answer to that is trickier than you might think.

Recent polls have reported seemingly contradictory information about public opinion on the mission. One recent survey showed a strong majority of Canadians preferring the bombing mission against ISIS to continue or be intensified, while another poll has suggested a plurality of Canadians agree with the Liberals' decision to end the airstrikes.

Neither of these polls is necessarily wrong — in fact, their differences may just have to do with the question being asked.

But that won't stop opponents and proponents of the Liberal plan to pick and choose the numbers to back their own arguments.

On Monday, Prime Minister Justin Trudeau, citing his party's campaign promise, announced his government would end the bombing mission but continue the aerial and refueling flights the Royal Canadian Air Force has been conducting since the end of 2014. The number of trainers deployed to the Middle East would also be increased.

Defence Minister Harjit Sajjan begins two days of meetings Wednesday with his NATO counterparts in Brussels. It's the first interaction between a Canadian cabinet minister and allies following the release of the government's new strategy for helping fight ISIS.

Support for Canada's ISIS mission3:43

Rona Ambrose, the interim leader of the Conservatives, who opposes the end of the bombing mission, called Trudeau's plan "absolutely shameful."

A poll published on Saturday from the Angus Reid Institute (ARI) suggests Ambrose may be onside with Canadian public opinion. The survey found that 63 per cent of Canadians felt that Canada's role in the fight against ISIS should be an increase in both bombing and training, or the continuation of the current levels of activity Canada's armed forces are conducting in the region.

Just 27 per cent wanted the bombing mission stopped and for only training to go ahead, while 11 per cent wanted nothing to do with the mission.

But a poll published by Le Devoir and Le Journal de Montréal on Tuesday and conducted by Léger found that 46 per cent of Canadians agreed with the end of Canada's participation in the airstrikes against ISIS, against 37 per cent who disagreed.

So do Canadians want the bombing mission in the Middle East to stop or not?

The form of a question

As is often the case with public opinion polling, the devil is in the details.

While the ARI poll provided respondents with a number of options, the Léger poll asked a simple yes-or-no question. That can have an impact on the way respondents think about their answers — though it doesn't make their answers any less truthful.

Another recent poll demonstrated this as well. A survey by Nanos Research for The Globe and Mail found just 29 per cent of Canadians chose "providing fighter jets to fly combat missions as part of the coalition" as their preferred role for Canada. Another 38 per cent chose training of some kind (in Iraq or not, Iraqis or Kurds), while nine per cent opted for surveillance and aircraft refueling missions.

Listen to the Pollcast podcast

In the latest episode of The Pollcast, Éric Grenier discusses differing ISIS-mission polls with Shachi Kurl, executive director of the Angus Reid Institute, and Christian Bourque, executive vice-president of Léger.

Like the ARI poll, a very small number of Canadians (nine per cent) wanted no role for Canada in the fight against ISIS.

Why the difference here? Two of the options in the ARI poll included training as well as bombing, with a third option excluding bombing. The Nanos poll did not make respondents make any either/or choices, instead asking about preferences. That extra nuance gave people more latitude to make their choice, but it did not mean that if they preferred training of Kurdish forces they were against bombing too.

CF-18 Hornets

Canada's CF-18 fleet, based out of Cold Lake, Alta., will return home soon. Canadians may or may not be pleased with that. (CBC)

A promise is a promise?

Though the Léger poll did not indicate that the Liberals had made a campaign promise to end the bombing, their yes-or-no question may have implied it to those aware of the government's pledge.

But other polls that have explicitly explained that ending the bombing mission was a campaign promise have shown similar results to Léger's latest numbers. A survey by Abacus Data from mid-January found that 48 per cent of Canadians wanted the Liberals to follow through on their promises to end the bombing mission and put more emphasis on training local troops. Just 35 per cent wanted the Liberals to break that promise.

Even a post-election poll by ARI at the end of October found a majority of Canadians supporting the Liberals implementing their campaign promise to end Canada's involvement in the air-bombing mission against ISIS.

This is an indication that Canadians are reluctant to tell parties to break a campaign promise once they form government. This may partly explain why the Liberals have placed so much emphasis on their promise when justifying the decision to pull Canada's six CF-18 fighter jets out of the Middle East. But partisanship still has an impact on Canadians' views, as across multiple polls Conservative voters have been in favour of the Liberals breaking this promise — and by significant margins.

Nevertheless, if an issue is an important one for Canadians with positions sharply entrenched on either side of the debate, these significant discrepancies between polls should be less likely to occur. This may suggest that the form of Canada's mission against ISIS is not a top priority for Canadians, just as long as the country is doing something.

What that thing should be depends on how you ask.

The poll by Léger was conducted for Le Devoir and Le Journal de Montréal between Feb. 1 and 4, 2016, interviewing 1,524 via the Internet. As the poll was conducted via an online panel, a margin of error does not apply.

The poll by the Angus Reid Institute was conducted between Jan. 27 and 31, 2016, interviewing 1,503 Canadians via the Internet. As the poll was conducted via an online poll, a margin of error does not apply.

The poll by Nanos Research was conducted for The Globe and Mail between Jan. 30 and Feb. 1, 2016, interviewing 1,000 Canadians online, after being contacted via the telephone. The margin of error associated with the sample is +/- 3.1 per cent, 19 times out of 20.

The poll by Abacus Data was conducted between Jan. 8 and 12, 2016, interviewing 1,500 Canadians via the Internet. As the poll was conducted via an online panel, a margin of error does not apply.