How the MPR News/Star Tribune/KARE 11 Minnesota poll was done

Methodology

The findings of this MPR News/Star Tribune/KARE 11 Minnesota poll are based on live interviews conducted Aug. 10 to Aug. 12 with 800 Minneapolis registered voters. That sample included interviews with 525 self-identified white registered voters and 146 African American registered voters. An additional 354 interviews were conducted Aug. 6 to Aug. 12 with African American registered voters in Minneapolis, for a total of 500 interviews. This is commonly referred to as an “oversample,” and allows for an apples-to-apples comparison of the responses of white voters and Black voters. This poll was conducted for the Star Tribune, MPR News and KARE 11 by Mason-Dixon Polling and Strategy Inc.

Those interviewed were randomly selected by computer from a phone-matched Minneapolis voter registration list that included both land line and cellphone numbers. For the sample of 800 Minneapolis registered voters, 29 percent of the interviews were conducted via land line and 71 percent via cellphone. For the sample of 500 African American registered voters, 26 percent of the interviews were conducted via land line and 74 percent via cellphone. 

The margin of sampling error for the sample of 800 Minneapolis registered voters, according to standards customarily used by statisticians, is no more than plus or minus 3.5 percentage points. This means there is a 95 percent probability that the "true" figure would fall within that range if all voters were surveyed. The margin of sampling error for the sample of 500 African American Minneapolis registered voters is no more than plus or minus 4.5 percentage points. The margin of error is higher for any subgroup, such as a gender or age grouping.

Sampling error does not take into account other sources of variation inherent in public opinion surveys, such as nonresponse, question wording or context effects. In addition, news events may have affected opinions during the period the poll was taken.

The self-identified party affiliation of the respondents of the sample of 800 Minneapolis registered voters is 62 percent Democrats, 10 percent Republicans and 28 percent independents or other. The self-identified party affiliation of the respondents of the sample of 500 African American Minneapolis registered voters is 63 percent Democrats, less than 1 percent Republicans and 37 percent independents or other.

The demographic profile of this poll of registered voters is an accurate reflection of their respective voter populations. This determination is based on more than 100 statewide polls conducted by Mason-Dixon in Minnesota over the past 32 years – a period that spans eight presidential election cycles that began in 1988.

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