Exit polls and quick count results from seven pollsters in Indonesia show Jakarta governor Joko Widodo as the winner in Indonesia’s presidential election.
According to the quick count results, which have proved accurate in the past, the candidate popularly known as Jokowi won the race by a margin of 3-5% from former military general Prabowo Subianto. Eleven pollsters have released quick counts. Prabowo also claims victory based on surveys released by four pollsters favourable to him.
What is the difference between exit polls and quick counts?
Dirga Ardiansa, a statistician and research manager at the Centre for Political Studies at the University of Indonesia, said that to predict the winner of presidential elections pollsters use three consecutive surveys: the popularity surveys, the exit poll and quick count. The quick count, based on sampling of the actual vote, is the most reliable.
Quick Count: “is a survey on the election results. Quick count samples are no longer individuals but the polling stations,” Dirga said.
The pollsters wait until their sample polling stations have counted the votes. The result of quick counts comes from the aggregate percentage of voters.
Margin of error: Margin of error is the amount of sampling error in the survey’s result. “In the context of the Indonesian election, if we take the total number of polling stations, which is 479,000, then taking 2,400 polling stations as samples will give you a 2% margin of error,” Dirga said. The more samples survey centres take, the smaller the margin of error and the more precise their data would be.
According to Dirga, of the 11 pollsters' published quick counts, Saiful Mujani Research Centre has the smallest margin of error. But for him, the most credible surveys come from the Kompas research and development team and RRI (Republic of Indonesia Radio) pollsters for their methodology and independence, he said.
“If we look at the four pollsters that show Prabowo leading, from the results they publish they still have many weaknesses,” he said. “We are not sure about their independence as well.”
He said the CSIS-Cyrus quick count is methodologically credible. “But we have to admit they are part of Jokowi’s campaign team, so there is a conflict of interest there.”
Exit Poll: “is a survey taken immediately after the respondents cast their votes”, Dirga said. The target respondents are people who have exited the poll booth and are asked who they voted for.
“This type of survey is relatively more accurate than popularity surveys because the respondent answered just after they have voted,” he said.
For example, the Centre for Strategic and International Studies with Cyrus had interviewers in 2,000 polling stations scattered in 34 provinces across Indonesia. In each polling station, they interviewed four people (two men and two women, based on Indonesia’s gender distribution).
Popularity surveys: Remember when Prabowo closed the gap between him and Jokowi in electability rates? Dirga said that these electability rates were based on pre-election surveys, or opinion polls. “The method of survey is to take samples before the election. Prospective voters are asked about their political preference,” he said.
Pre-election surveys are the weakest in predicting who would win the race, Dirga said. “Because it’s done before the election, people can still change their mind.”