DOI: 10.3886/e161581v1-176683
title: 2020 Treasure State (Montana) Election Surveys

description: The Treasure State 2020 Pre-Election Survey was conducted by the
HELPS Lab of Montana State University-Bozeman between September 14 and October 2,
2020. The original population for the survey was Montana voters who registered by
August 20, 2020, and were deemed active by the Montana Secretary of State. We
stratified the sample by state house districts, and then drew a random sample
of 9,000 voters proportionally from these strata. Sampled individuals received
a questionnaire by mail and were asked to return the questionnaire via a prepaid
business reply envelope. Respondents returned 1,789 surveys, a response rate of
20.2% based on 8,836 deliverable addresses. The Treasure State 2020
Post-Election Survey, also conducted by the HELPS Lab, used a panel design that
returned to the individuals who responded to the Pre-Election Survey. This survey was in the field from November 4-25, 2020. Of the 1,789 original respondents, 1,069
completed the post-election questionnaire, for a response rate of 59.8%. The
procedures for the Post-Election Survey otherwise paralleled those for the
Pre-Election Survey.

<br><br>The number of individuals voting in the 2020 general election in
Montana was 612,075, according to information from the Montana Secretary of
State. We have adjusted the overall survey margin of error (MoE) for design
effect owing to our subsequent use of weights in calculating results. This
adjustment has the consequence of making the margin of error substantially
larger than it otherwise would be. For the pre-election sample, this results in
a MoE of <b>+/- 3.7</b> percentage points, using a confidence level of 95% and
a response distribution of 50% (the most conservative estimate) with the given population
size. For the post-election sample, the corresponding MoE is <b>+/- 6.0</b>
percentage points. We note that these figures are overall approximations given
sampling stratification and different response options and response patterns
for specific questions. <br>

<br>This project was funded by over 100 individual donors to the Montana State University Alumni
Foundation and by Montana State University.
description: To mitigate
non-response bias in the sample, the researchers chose to weight the sample
using iterative proportional fitting, or raking. Raking generates weights that
adjust the sample in subsequent analyses so that the sample more closely
resembles the target population, in this case individuals who voted in the 2020
Montana elections. Weights are generated by forcing sample margins to
approximate population margins for key demographic characteristics. The
researchers generated weights for individuals using age, education, gender,
media market, self-reported 2020 presidential vote choice, and self-reported
vote on the state marijuana measure I-190. Population margins for education and
gender were obtained using data from the U.S. Census Bureau’s 2018 Current
Population Survey Voter Supplement. Population margins for 2020 presidential
vote choice and vote on the state marijuana measure were based on vote returns
retrieved from the Montana Secretary of State’s website. Population margins for
media market and age came from public data also available from the Montana
Secretary of State. <br><br>The
pre-election weight used in the current data release differs slightly from the
weight used by the investigators prior to the 2020 election. Consequently, the
full set of results differs from earlier-published results in minor ways. The
updated weight incorporates better information about “likely” voters by
including individuals who actually voted in the election. Therefore, all
results are meant to represent the views of Montana voters. Survey respondents
were filtered prior to the creation of survey weights to retain only
respondents who actually voted in the 2020 general election. This left 1,765 respondents
for the pre-election survey and 1,066 respondents for the post-election survey. The weights used in the presented frequencies and marginal percentages are prewgt2 and postwgt2.
description: Response Rates: Pre-election survey: 20.2%<br>Post-election survey (panel): 59.8%
description: The original universe for the poll was Montana voters who registered by August 20, 2020, and were deemed active by the Montana Secretary of State. For the pre-election survey, the sample was stratified by state House districts, and then a random sample of 9,000 voters was drawn proportionally from these strata. For the post-election survey, researchers used a panel design, meaning they re-surveyed individuals who had completed the pre-election questionnaire. The data posted here have been filtered and weighted to represent individuals who actually voted in the 2020 general election in Montana. Therefore, the final universe is actual Montana 2020 voters.
description: Montana voters in 2020 general election. Smallest Geographic Unit: State
description: mail questionnaire; Data collected via mail surveys in two waves -- one prior to the election and another following the election