Brazil's MDA institute will publish on Saturday (24) its last voting intention poll before the presidential runoff between Lula (PT) and Flávio Bolsonaro (PL), scheduled for Sunday (25), according to CartaCapital. The survey is commissioned by the National Transport Confederation (CNT) and will be the institute's final reading of the race before Brazilians vote.

The poll will be based on 2,002 face-to-face interviews conducted from Wednesday to Friday this week, with a margin of error of 2.2 percentage points, CartaCapital reports. For now, only the study's design is confirmed: sample size, fieldwork dates and margin. The voting intention figures themselves will be released on Saturday.

The institute's previous round, published last Friday (16), showed Flávio Bolsonaro with 50.5% of valid votes against 49.5% for Lula. The one-point gap fell within the margin of error, amounting to a statistical tie, the magazine said. In Brazilian polls, valid votes exclude blank and null ballots and undecided voters, so percentages run higher than in total voting intention figures.

MDA will not be the only institute in the field during the final stretch. CartaCapital also reports that AtlasIntel is preparing its last survey before the runoff, which should give voters a set of final readings on the presidential race on the eve of the vote.

A few practical cautions apply when reading Saturday's numbers. A lead of one or two points, against a 2.2-point margin of error, is not enough to say who is ahead. It is safer to compare polls from the same institute over time, check whether figures refer to total or valid votes, and look up the survey's registration with the Superior Electoral Court (TSE), which is mandatory for any poll published during the election period.