The latest estimates of General Election voting intent from IHP’s SLOTS MRP model (revised 01/2024) show no substantial changes in August compared to the previous month. The SJB and NPP/JVP led and were in a statistical tie with 29% and 28% of voter support, respectively, followed by the SLPP with 19%, the UNP with 9%, and ITAK with 4%. Support for the SJB and NPP/JVP dropped by 3 and 2 percent, respectively, in August compared to July, but the changes are within the margin of error. The August estimates are provisional and carry a margin of error of 2–3% for the two leading parties. 

SLOTS polling director, Dr. Ravi Rannan-Eliya commented: “Our general election voting intent survey reveals substantially more support for the SLPP in a general election than for their presidential candidate, and similarly more support for Ranil Wickremesinghe’s presidential candidacy than for the UNP. It would be unwise to write off the SLPP as a political force, since many SLPP voters appeared in August to be switching their presidential vote to Ranil Wickremesinghe. Of course, they could also do this using their second preference votes, which suggests limited voter understanding of that option.”

Compared to IHP’s August release, the estimates of NPP/JVP and SJB support in July 2024 were revised downward by 2 points each.

These estimates are for all adults, not just for likely voters. They are based on the January 2024 revision of the IHP SLOTS Multilevel Regression and Poststratification (MRP) model. IHP is working on improving its likely voter model and will resume the release of voting intent in likely voters in a future update. It should be noted that differences in voting intent shares between all adults and likely voters have typically been 1–2% for most estimates in the past two years.

This August 2024 update is based on 19,721 interviews conducted with adults across Sri Lanka since Oct. 2021, including 1,153 interviews during August. IHP’s SLOTS MRP methodology first estimates the relationship between a wide variety of characteristics about respondents and their opinions – in this case, ‘If there was a General Election today, which party would you vote for?’– in a multilevel statistical model. It then uses a large data file that is calibrated to the national population to predict voting intent in each month since Oct. 2021, according to what the multilevel model says about their probability of voting for various parties (‘post-stratification’) at each point in time. The multilevel model was estimated 100 times to reflect underlying uncertainties in the model and to obtain margins of error. The voting intent results for previous months have changed in this update as more data were collected after the last release, and these changes are within the margin of error.

About IHP

IHP is solely responsible for commissioning and designing the survey, and it takes full responsibility for it. IHP is an independent, non-partisan research centre based in Colombo, Sri Lanka. The SLOTS lead investigator is Dr Ravi Rannan-Eliya of IHP, who was trained in public opinion polling at Harvard University and has conducted numerous surveys over three decades, both in and outside Sri Lanka. 

Methodology details

SLOTS combines interviews from a national sample of adults (ages 18 and over) reached by random digit dialling of mobile numbers, and others coming from a national panel of respondents who were previously recruited through random selection and face-to-face interviews. IHP estimates voting intent using an adaptation of Multilevel Regression and Post-Stratification (MRP), with multiple imputations to account for uncertainties in its modelling, exploiting data from all SLOTS interviews to estimate voting in a particular month. 

The August 2024 MRP estimates are based on 19,721 interviews conducted from 1 October 2021–2 September 2024, including 1,153 interviews conducted in August 2024. The margin of error is assessed as 1.1–1.8% for the UNP, SLPP, SLFP, SLMC, CWC, ITAK and the “other” parties, and 2.1–2.6% for NPP/JVP and SJB. A total of 100 bootstraps were used to estimate margins of error.

MRP is a method that is increasingly used by polling firms in other countries to leverage small samples, most notably by YouGov which used it to forecast results of the UK Brexit Referendum and recent UK general elections. All estimates are adjusted to ensure the sample matches the national population with respect to age, sex, ethnicity, socioeconomic status, education, geographical location, and voting in the 2019 Presidential and 2020 General Elections.

Funding

SLOTS fieldwork since 2021 has been supported by a range of funders, who play no role in question design, data analysis, or reporting. Past funders have included the Neelan Tiruchelvam Trust, Asia Foundation, European Commission, UK National Institute for Health and Care Research, the Foundation Open Society Institute, and others. Current fieldwork is supported by funding from the Velux Stiftung foundation, New York University Abu Dhabi, and the IHP Public Interest Research Fund. The survey findings and IHP reporting do not necessarily reflect the views or positions of past and present funders. Interested parties can contact IHP for more detailed data and results.