2018 Montana Election Surveys (MSU-MTN)

The MSU-MTN pre-election survey was conducted by the Human Ecology Learning & Problem Solving (HELPS) Lab of Montana State University-Bozeman between September 15 and October 6, 2018. The population for the poll was Montana voters who registered by August 14, 2018. The sample was stratified by state House districts, and then a random sample of 10,400 voters was drawn proportionally from these strata. Sampled individuals received a questionnaire by mail and were asked to return the questionnaire via a self-addressed stamped envelope. Respondents returned 2,079 surveys, a response rate of slightly over 20% based on 10,215 deliverable addresses.

The population size was 686,791 registered voters. This resulted in a margin of error (MOE) of approximately +/- 2 percentage points. Please note that this figure is an overall approximation given sampling stratification and different response options and response patterns for specific questions. Using a raking method, the data were weighted by age, media market, marital status by gender, and education to match U.S. Census Bureau data on registered Montana voters. Data were also weighted on 2016 presidential vote choice to match vote returns reported by the Montana Secretary of State.

The MSU-MTN post-election survey was similarly conducted by the HELPS Lab of Montana State University-Bozeman between November 8 and December 14, 2018. Researchers used a panel design, meaning they re-surveyed individuals who had completed the pre-election questionnaire. Respondents returned 1,424 completed questionnaires for a response rate of approximately 68%. The population of registered voters at the time of the election was 711, 844, which produced an overall MOE of approximately +/- 2.6 percentage points. The weights remained the same except for replacing 2016 presidential vote choice with 2018 Senate vote choice.