The Sun Poll is conducted by Potomac Inc., a nonpartisan, independent firm based in Bethesda.
The company has completed 15 statewide surveys for the newspaper since 1998, and it has performed independent surveys for other media outlets since 1986. It is not involved in any of the statewide races for any candidate or political party.
Potomac Inc. identifies likely voters by purchasing the most current available data from a commercial vendor, which compiles information from county boards of elections, and creating a call list of those who have voted in previous elections.
Using previous elections as a guide, the company estimates turnout and sets quotas for poll respondents in each geographic area of the state based on party. The quotas are set before voters are contacted by telephone.
After the results are collected, the sample is statistically weighted to ensure race, gender, political party and geography are accurately accounted for.
The current Sun Poll surveyed 1,008 likely voters, and has a margin of error of 3.2 percentage points for most questions. That means that 95 times out of 100, the poll result for a given question would be within 3.2 points of the result that could be obtained if the entire population of Maryland voters was surveyed.
For questions involving the Democratic Primary, the sample size was 474 likely voters, with a margin of error of 4.6 points.