Unreliability Of Opinion Polls Bringing More Political Surprises

Several times this year, we have witnessed 'surprise' or even 'shock' outcomes from general elections, due to the unreliability of opinion polls, late surges by seemingly weaker parties or candidates, or sharp declines in support for incumbents.

This demonstrates that opinion polls need to be viewed with a great deal of caution, even in developed states, where voter surveys should generally be more accurate, due to greater political freedoms, better historical data, and – in theory – more sophisticated methodologies.

Examples of surprise election outcomes this year include:

Sri Lanka: January's snap presidential election saw the surprise victory of opposition candidate Maithripala Sirisena, which would have been unthinkable only a few months previously – not least because Sirisena was from the defeated president Mahinda Rajapaksa's party. Also surprising was that Rajapaksa himself conceded defeat very quickly, and did not try to contest the results.

Israel: Prime Minister Benjamin Netanyahu's Likud party performed better than expected, winning a plurality of seats in the March 17 election, thus defying predictions that the opposition Zionist Union would emerge with the most seats.

Nigeria: Muhammadu Buhari of the opposition All People's Congress defeated incumbent President Goodluck Jonathan in March's elections, despite all the advantages that the incumbent typically enjoys. As with Sri Lanka, the outgoing president quickly conceded defeat, and there was minimal violence. This last point was highly significant, because past Nigerian elections were highly contentious affairs, accompanied by violence.

United Kingdom: Prime Minister David Cameron's Conservative Party's majority victory in May was a major surprise, given that all polls had pointed to a hung parliament, with many surveys saying that the opposition Labour Party would emerge as the largest in parliament.

Poland: The opposition candidate Andrzej Duda surprisingly defeated incumbent President Bronislaw Komorowski, who had widely been considered a shoo-in ahead of May's presidential election. Duda's Law and Justice Party (PiS) also won a parliamentary majority in October's legislative elections, becoming the first party to do so in the post-Communist era. Our own forecast had been for a PiS plurality.

Argentina: Second-placed candidate Mauricio Macri did much better than opinion polls expected in the first-round presidential election on October 25. As a result, we now believe that Macri can prevail in round two on November 22, beating first-placed Daniel Scioli.

Canada: The opposition Liberal Party surprised virtually everyone by winning a majority in the October 19 election, ousting the Conservatives. Polls had generally pointed to a Liberal plurality.

Turkey: The Justice and Development Party (AKP), having surprised most observers by losing its parliamentary majority in June elections, surprised on the upside by regaining its majority in the November 1 election.

In truth, political observers and investors have little choice but to rely on opinion polls, given the difficulties in gathering data independently of the pollsters. That being the case, we are preparing a special feature on opinion polls, so that our readers can get a better understanding on their strengths and weaknesses.  We will post some of the findings on this blog in due course.