In last presidential elections, polls overestimated Libertarian Guevara’s support and underestimated PAC’s

As Costa Rica’s election season enters its final stretch, candidates have greeted the slew of recent polls with disbelief or encouragement, often based on their own standings.

National Liberation Party (PLN) nominee Johnny Araya was incredulous over a January poll in the daily La Nación that put the former front-runner in a virtual tie with the Broad Front Party’s José María Villalta and the Libertarian Movement Party’s Otto Guevara.

“For the first time, I reject the results of a poll and I reject these categorically,” Araya said.

A Tico Times analysis of polls leading up to the 2010 election indicated that the polls were relatively accurate. Polls averaged 46.1 percent for PLN candidate Laura Chinchilla, who won with 46.9 percent of the vote on Election Day.

Polls missed by the widest margin on Citizen Action Party (PAC) candidate Ottón Solís. Polls averaged 13.1 percent support for Solís, and he went on to garner 25.1 percent. Solís ended by jumping ahead of Libertarian Movement Party candidate Guevara, who averaged 26.3 percent support in the polls, yet only won 20.9 percent of the vote.

The events of the campaign may explain why Ottón Solís outperformed his polls on Election Day 2010. He won a number of last-minute endorsements only a few weeks before the election.

The Tico Times looked at 10 polls from Nov. 26, 2009 through Jan. 26, 2010. Several polls were not included as their information was no longer available. Explore the graphic below.

CID-Gallup misestimated the top three candidates’ final percentage by an average of 6.6 percent. UNIMER-La Nación misestimated their percentages by 8.2 percent.